Blog entries - Codeforces

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Supermagzzz's blog

Codeforces Round #725 (Div. 3) Editorial

By Supermagzzz, history, 4 years ago, translation, In English

Tutorial

Solution

#include <bits/stdc++.h>
#include "random"

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

void solve() {
    int n;
    cin >> n;
    vector<int> v(n);
    for (int &e : v) {
        cin >> e;
    }
    int maxPos = max_element(v.begin(), v.end()) - v.begin();
    int minPos = min_element(v.begin(), v.end()) - v.begin();
    cout << min({
            max(maxPos, minPos) + 1,
            (n - 1) - min(maxPos, minPos) + 1,
            (n - 1) - maxPos + minPos + 2,
            (n - 1) - minPos + maxPos + 2
    }) << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}

1538B - Friends and Candies

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

void solve() {
  int n;
  cin >> n;
  vector<int> a(n);
  int s = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    s += a[i];
  }
  if (s % n != 0) {
    cout << "-1" << endl;
    return;
  }
  s /= n;
  int res = 0;
  for (int i = 0; i < n; i++) {
    if (s < a[i]) {
      res++;
    }
  }
  cout << res << endl;
}

int main() {
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}

1538C - Number of Pairs

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
#include "random"

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

void solve() {
    int n, l, r;
    cin >> n >> l >> r;
    vector<int> v(n);
    for (int &e : v) {
        cin >> e;
    }
    sort(v.begin(), v.end());
    ll ans = 0;
    for (int i = 0; i < n; i++) {
        ans += upper_bound(v.begin(), v.end(), r - v[i]) - v.begin();
        ans -= lower_bound(v.begin(), v.end(), l - v[i]) - v.begin();
        if (l <= 2 * v[i] && 2 * v[i] <= r) {
            ans--;
        }
    }
    cout << ans / 2 << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}

1538D - Another Problem About Dividing Numbers

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

const int N = 50'000;

bool isPrime[N];
vector<int> primes;

void precalc() {
  fill(isPrime + 2, isPrime + N, true);
  for (int i = 2; i * i < N; i++) {
    for (int j = i * i; j < N; j += i) {
      isPrime[j] = false;
    }
  }
  for (int i = 2; i < N; i++) {
    if (isPrime[i]) {
      primes.push_back(i);
    }
  }
}

int calcPrime(int n) {
  int res = 0;
  for (int i : primes) {
    if (i * i > n) {
      break;
    }
    while (n % i == 0) {
      n /= i;
      res++;
    }
  }
  if (n > 1) {
    res++;
  }
  return res;
}

map<int, int> decompose(int n) {
  map<int, int> a;
  for (int i : primes) {
    if (i * i > n) {
      break;
    }
    int p = 0;
    while (n % i == 0) {
      n /= i;
      p++;
    }
    if (p > 0) {
      a[i] = p;
    }
  }
  if (n > 1) {
    a[n] = 1;
  }
  return a;
}

bool check(const map<int, int> &divs,
           map<int, int>::const_iterator it,
           map<int, int> &divsA,
           map<int, int> &divsB,
           int low,
           int high,
           int k) {
  if (it == divs.end()) {
    return __builtin_popcount(low) <= k && k <= high;
  }
  for (int p = 0; p <= it->second; p++) {
    int pa = divsA[it->first];
    int pb = divsB[it->first];
    int nextLow = low;
    if (p != pa) {
      nextLow |= 1;
    }
    if (p != pb) {
      nextLow |= 2;
    }
    if (check(divs, next(it), divsA, divsB, nextLow, high + pa + pb - 2 * p, k)) {
      return true;
    }
  }
  return false;
}

void solve() {
  int a, b, k;
  cin >> a >> b >> k;
  int g = __gcd(a, b);
  int low = 0;
  int high = 0;
  {
    int t;
    int ta = 1;
    while ((t = __gcd(a, g)) != 1) {
      a /= t;
      ta *= t;
    }
    high += calcPrime(a);
    if (a != 1) {
      low |= 1;
    }
    a = ta;
  }
  {
    int t;
    int tb = 1;
    while ((t = __gcd(b, g)) != 1) {
      b /= t;
      tb *= t;
    }
    high += calcPrime(b);
    if (b != 1) {
      low |= 2;
    }
    b = tb;
  }
  auto divs = decompose(g);
  auto divsA = decompose(a);
  auto divsB = decompose(b);
  cout << (check(divs, divs.begin(), divsA, divsB, low, high, k) ? "YES" : "NO") << endl;
}

int main() {
  precalc();

  int t;
  cin >> t;
  while (t--) {
    solve();
  }

  return 0;
}

1538E - Funny Substrings

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
#include "random"

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

vector<string> split(const string& s, char p) {
    vector<string> res(1);
    for (char c : s) {
        if (c == p) {
            res.emplace_back();
        } else {
            res.back() += c;
        }
    }
    return res;
}

struct Word {
    ll len;
    ll cnt;
    string s;
};

string getFirst(string s) {
    if (s.size() < 3) {
        return s;
    }
    return s.substr(0, 3);
}

string getLast(string s) {
    if (s.size() < 3) {
        return s;
    }
    return s.substr(s.size() - 3, 3);
}

int count(const string& s, const string& p) {
    int cnt = 0;
    for (int i = 0; i + p.size() <= s.size(); i++) {
        if (s.substr(i, p.size()) == p) {
            cnt++;
        }
    }
    return cnt;
}

Word merge(const Word& a, const Word& b) {
    Word c;
    c.len = a.len + b.len;
    c.s = a.s + b.s;
    c.cnt = a.cnt + b.cnt + count(getLast(a.s) + getFirst(b.s), "haha");
    if (c.s.size() >= 7) {
        c.s = getFirst(c.s) + "@" + getLast(c.s);
    }
    return c;
}

void solve() {
    int n;
    cin >> n;
    map<string, Word> vars;
    ll ans = 0;
    for (int i = 0; i < n; i++) {
        string var;
        cin >> var;
        string opr;
        cin >> opr;
        if (opr == "=") {
            string a, plus, b;
            cin >> a >> plus >> b;
            vars[var] = merge(vars[a], vars[b]);
        } else {
            string str;
            cin >> str;
            Word word;
            word.len = str.length();
            word.cnt = count(str, "haha");
            word.s = str;
            vars[var] = word;
        }
        ans = vars[var].cnt;
    }
    cout << ans << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}

1538F - Interesting Function

Author: Supermagzzz, Stepavly

Tutorial

Solution

#include <iostream>

using namespace std;

void solve () {
  int L, R;
  cin >> L >> R;

  int ans = 0;
  while (L != 0 || R != 0) {
    ans += R - L;
    L /= 10;
    R /= 10;
  }
  cout << ans << '\n';
}

int main () {
  ios::sync_with_stdio(false);
  cin.tie(0);
  
  int testc;
  cin >> testc;

  for (int i = 0; i < testc; i++) {
    solve();
  }
}

1538G - Gift Set

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
#include "random"

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

void solve() {
    ll x, y, a, b;
    cin >> x >> y >> a >> b;
    ll l = 0, r = 1e9 + 100;
    if (a == b) {
        cout << min(x, y) / a << "\n";
        return;
    }
    if (a < b) {
        swap(a, b);
    }
    while (r - l > 1) {
        ll m = (l + r) / 2;
        ll right = floorl((x - m * b) * 1.0l / (a - b));
        ll left = ceill((y - m * a) * 1.0l / (b - a));
        if (max(left, 0ll) <= min(right, m)) {
            l = m;
        } else {
            r = m;
        }
    }
    cout << l << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}

Full text and comments »

Tutorial of Codeforces Round 725 (Div. 3)

Supermagzzz
4 years ago
278

Codeforces Round #719 (Div. 3) Editorial

By Supermagzzz, 4 years ago, translation, In English

1520A - Do Not Be Distracted!

Authors: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

void solve() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    for (char c = 'A'; c <= 'Z'; c++) {
        int first = n;
        int last = -1;
        for (int i = 0; i < n; i++) {
            if (s[i] == c) {
                first = min(first, i);
                last = max(last, i);
            }
        }
        for (int i = first; i <= last; i++) {
            if (s[i] != c) {
                cout << "NO\n";
                return;
            }
        }
    }
    cout << "YES\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}

1520B - Ordinary Numbers

Authors: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
using namespace std;

using ll = long long;

void solve() {
  int n;
  cin >> n;
  int res = 0;
  for (ll pw = 1; pw <= n; pw = pw * 10 + 1) {
    for (int d = 1; d <= 9;  d++) {
      if (pw * d <= n) {
        res++;
      }
    }
  }
  cout << res << endl;
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

1520C - Not Adjacent Matrix

Authors: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
using namespace std;

void solve() {
  int n;
  cin >> n;
  if (n == 1) {
    cout << "1" << endl;
    return;
  } else if (n == 2) {
    cout << "-1" << endl;
    return;
  }
  vector<vector<int>> a(n, vector<int>(n));
  a[0][0] = 1;
  a[n - 1][n - 1] = n * n;
  int x = n * n - 1;
  for (int i = 1; i + 1 < n; i++) {
    for (int j = i; j >= 0; j--, x--) {
      a[i - j][j] = x;
    }
  }
  x = 2;
  for (int j = n - 2; j > 0; j--) {
    for (int i = 0; i < n - j; i++, x++) {
      a[n - i - 1][j + i] = x;
    }
  }
  for (int i = n - 1; i >= 0; i--, x++) {
    a[i][n - i - 1] = x;
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cout << a[i][j] << " ";
    }
    cout << endl;
  }
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

1520D - Same Differences

Authors: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
using namespace std;

void solve() {
  int n;
  cin >> n;
  map<int, int> a;
  long long res = 0;
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    x -= i;
    res += a[x];
    a[x]++;
  }
  cout << res << endl;
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

1520E - Arranging The Sheep

Authors: Supermagzzz, Stepavly

Tutorial

Solution

#include<bits/stdc++.h>
 
using namespace std;
 
void solve()
{
	int n;
	cin >> n;
	string s;
	cin >> s;
	int cnt = 0;
	for(auto x : s)
		cnt += (x == '*' ? 1 : 0);
	int pos = -1;
	int cur = -1;
	for(int i = 0; i < n; i++)
	{
	 	if(s[i] == '*')
	 	{
	 	    cur++;
	 	    if(cur == cnt / 2)
	 	    	pos = i;
	 	}	
	}
	long long ans = 0;
	cur = pos - cnt / 2;
	for(int i = 0; i < n; i++)
		if(s[i] == '*')
		{
		 	ans += abs(cur - i);
		 	cur++;
		}
	cout << ans << endl;
}
 
int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int tc = 1;
	cin >> tc;
	for(int i = 0; i < tc; i++)
	{
	 	solve();
	}
}

1520F1 - Guess the K-th Zero (Easy version)

Authors: Supermagzzz, Stepavly

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

void calc(int l, int r, int k) {
    if (l == r) {
        cout << "! " << l << endl;
        return;
    }
    int m = (l + r) / 2;
    cout << "? " << l << " " << m << endl;
    int sum;
    cin >> sum;
    if ((m - l + 1) - sum >= k) {
        calc(l, m, k);
    } else {
        calc(m + 1, r, k - (m - l + 1) + sum);
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, t, k;
    cin >> n >> t >> k;
    calc(1, n, k);
}

1520F2 - Guess the K-th Zero (Hard version)

Authors: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

#define forn(i, n) for (int i = 0; i < int(n); i++)

map<pair<int,int>, int> cache;

void dec(int pos, int L, int R) {
    cache[{L, R}]--;

    if (L != R) {
        int M = (L + R) / 2;
        if (pos <= M)
            dec(pos, L, M);
        else
            dec(pos, M + 1, R);
    }
}

int main() {
    int n, cases;
    cin >> n >> cases;
    forn(case_, cases) {
        int k;
        cin >> k;
        int L = 0, R = n - 1;
        while (L != R) {
            int M = (L + R) / 2;
            
            pair<int,int> range = make_pair(L, M);
            if (cache.count(range) == 0) {
                cout << "? " << range.first + 1 << " " << range.second + 1 << endl;
                cin >> cache[range];
                cache[range] = range.second - range.first + 1 - cache[range];
            }

            int value = cache[range];
            if (k <= value)
                R = M;
            else {
                k -= value;
                L = M + 1;
            }
        }

        cout << "! " << L + 1 << endl;
        dec(L, 0, n - 1);
    }
}

1520G - To Go Or Not To Go?

Authors: Supermagzzz, Stepavly, Aris

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using cd = complex<ld>;

const int MAX_N = 2010;

int dd[4][2] = {
        {1, 0},
        {0, 1},
        {-1, 0},
        {0, -1}
};

void bfs(int sx, int sy, vector<vector<int>> &d, vector<vector<int>> &a) {
    int n = d.size();
    int m = d[0].size();
    queue<pair<int, int>> q;
    q.push({sx, sy});
    d[sx][sy] = 1;
    while (!q.empty()) {
        auto [x, y] = q.front();
        q.pop();
        for (auto [dx, dy] : dd) {
            int tx = x + dx;
            int ty = y + dy;
            if (tx >= 0 && ty >= 0 && tx < n && ty < m && d[tx][ty] == 0 && a[tx][ty] != -1) {
                d[tx][ty] = d[x][y] + 1;
                q.push({tx, ty});
            }
        }
    }
    for (auto &e : d) {
        for (auto &i : e) {
            i--;
        }
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m, w;
    cin >> n >> m >> w;
    vector<vector<int>> a(n, vector<int>(m));
    vector<vector<int>> d1(n, vector<int>(m));
    vector<vector<int>> d2(n, vector<int>(m));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> a[i][j];
        }
    }
    bfs(0, 0, d1, a);
    bfs(n - 1, m - 1, d2, a);
    ll bestFinish = 1e18;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (d2[i][j] != -1 && a[i][j] >= 1) {
                bestFinish = min(bestFinish, a[i][j] + w * 1ll * d2[i][j]);
            }
        }
    }
    ll ans = w * 1ll * d1[n - 1][m - 1];
    if (d1[n - 1][m - 1] == -1) {
        ans = 1e18;
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (d1[i][j] != -1 && a[i][j] >= 1 && bestFinish != 1e18) {
                ans = min(ans, w * 1ll * d1[i][j] + a[i][j] + bestFinish);
            }
        }
    }
    if (ans == 1e18) {
        cout << -1;
    } else {
        cout << ans;
    }
}

Full text and comments »

Tutorial of Codeforces Round 719 (Div. 3)

+125

Supermagzzz
4 years ago
198

Codeforces Round #713 (Div. 3) Editorial

By Supermagzzz, history, 4 years ago, translation, In English

1512A - Spy Detected!

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

void solve() {
    int n;
    cin >> n;
    vector<int> v(n);
    for (int &e : v) {
        cin >> e;
    }
    vector<int> a = v;
    sort(a.begin(), a.end());
    for (int i = 0; i < n; i++) {
        if (v[i] != a[1]) {
            cout << i + 1 << "\n";
        }
    }
}

int main() {
    int n;
    cin >> n;
    while (n--) {
        solve();
    }
    return 0;
}

1512B - Almost Rectangle

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

#define forn(i, n) for (int i = 0; i < int(n); i++)

int main() {    
    int t;
    cin >> t;
    forn(tt, t) {
        int n;
        cin >> n;
        vector<string> f(n);
        vector<pair<int,int>> p;
        forn(i, n) {
            cin >> f[i];
            forn(j, n)
                if (f[i][j] == '*')
                    p.push_back({i, j});
        }

        p.push_back(p[0]);
        p.push_back(p[1]);
        if (p[0].first == p[1].first) {
            p[2].first = (p[2].first + 1) % n;
            p[3].first = (p[3].first + 1) % n;
        } else if (p[0].second == p[1].second) {
            p[2].second = (p[2].second + 1) % n;
            p[3].second = (p[3].second + 1) % n;
        } else
            swap(p[2].first, p[3].first);

        f[p[2].first][p[2].second] = '*';
        f[p[3].first][p[3].second] = '*';
        forn(i, n)
            cout << f[i] << endl;
    }
}

1512C - A-B Palindrome

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
using namespace std;

void no() {
  cout << "-1" << endl;
}

void solve() {
  int a, b;
  cin >> a >> b;
  string s;
  cin >> s;
  for (int times = 0; times < 2; times++) {
    for (int i = 0; i < (int) s.size(); i++) {
      int j = (int) s.size() - i - 1;
      if (s[i] != '?') {
        if (s[j] == '?') {
          s[j] = s[i];
        } else if (s[i] != s[j]) {
          no();
          return;
        }
      }
    }
    reverse(s.begin(), s.end());
  }
  a -= count(s.begin(), s.end(), '0');
  b -= count(s.begin(), s.end(), '1');
  int ques = count(s.begin(), s.end(), '?');
  bool emptyMid = (s.size() % 2 == 1 && s[s.size() / 2] == '?');
  if (a < 0 || b < 0 || a + b != ques || (emptyMid && a % 2 == 0 && b % 2 == 0)) {
    no();
    return;
  }
  if (a % 2 == 1 || b % 2 == 1) {
    int i = s.size() / 2;
    if (s[i] != '?') {
      no();
      return;
    }
    s[i] = (a % 2 == 1 ? '0' : '1');
    if (a % 2 == 1) {
      a--;
    } else {
      b--;
    }
  }
  if (a % 2 == 1 || b % 2 == 1) {
    no();
    return;
  }
  for (int i = 0; i < (int) s.size(); i++) {
    if (s[i] == '?') {
      int j = s.size() - i - 1;
      if (a > 0) {
        a -= 2;
        s[i] = s[j] = '0';
      } else {
        b -= 2;
        s[i] = s[j] = '1';
      }
    }
  }
  cout << s << endl;
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

1512D - Corrupted Array

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
using namespace std;

void no() {
  cout << "-1" << endl;
}

void solve() {
  int n;
  cin >> n;
  vector<int> b(n + 2);
  for (int &x : b) {
    cin >> x;
  }

  multiset<int> have(b.begin(), b.end());
  long long sum = accumulate(b.begin(), b.end(), 0LL);
  for (int x : b) {
    have.erase(have.find(x));
    sum -= x;
    if (sum % 2 == 0 && sum <= 2'000'000'000 && have.find(sum / 2) != have.end()) {
      have.erase(have.find(sum / 2));
      for (int y : have) {
        cout << y << " ";
      }
      cout << endl;
      return;
    }
    sum += x;
    have.insert(x);
  }
  no();
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

1512E - Permutation by Sum

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void solve() {
    int n, l, r, s;
    cin >> n >> l >> r >> s;
    l--; r--;
    for (int first = 1; first + (r - l) <= n; first++) {
        int sum = 0;
        for (int i = l; i <= r; i++) {
            sum += first + (i - l);
        }
        if (sum <= s && s - sum <= r - l + 1) {
            int needAdd = r - (s - sum) + 1;
            vector<int> ans(n);
            set<int> non_blocked;
            for (int i = 1; i <= n; i++) {
                non_blocked.insert(i);
            }
            for (int i = l; i <= r; i++) {
                ans[i] = first + (i - l);
                if (i >= needAdd) {
                    ans[i]++;
                }
                non_blocked.erase(ans[i]);
            }
            if (ans[r] > n) {
                continue;
            }
            non_blocked.erase(ans[r]);
            for (int i = 0; i < l; i++) {
                ans[i] = *non_blocked.begin();
                non_blocked.erase(non_blocked.begin());
            }
            for (int i = r + 1; i < n; i++) {
                ans[i] = *non_blocked.begin();
                non_blocked.erase(non_blocked.begin());
            }
            for (int i : ans) {
                cout << i << " ";
            }
            cout << "\n";
            return;
        }
    }
    cout << "-1\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    int n;
    cin >> n;
    while (n--) {
        solve();
    }
}

1512F - Education

Author: sodafago

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

void solve() {
    int n, c;
    cin >> n >> c;
    vector<int> a(n);
    vector<int> b(n - 1);
    for (int &e : a) {
        cin >> e;
    }
    for (int &e : b) {
        cin >> e;
    }
    b.push_back(0);
    ll ans = 1e18;
    ll cur = 0;
    ll bal = 0;
    for (int i = 0; i < n; i++) {
        ans = min(ans, cur + max(0ll, c - bal + a[i] - 1) / a[i]);
        ll newDays = max(0ll, b[i] - bal + a[i] - 1) / a[i];
        cur += newDays + 1;
        bal += a[i] * newDays - b[i];
    }
    cout << ans << "\n";
}

int main() {
    int n;
    cin >> n;
    while (n--) {
        solve();
    }
    return 0;
}

1512G - Short Task

Author: MikeMirzayanov

Tutorial

Solution

#include <bits/stdc++.h>
using namespace std;

const int N = (int) 1e7 + 100;

long long s[N];
int d[N];
int ans[N];

int main() {
  fill(d, d + N, -1);
  d[1] = 1;
  for (int i = 2; i * i < N; i++) {
    if (d[i] == -1) {
      d[i] = i;
      for (int j = i * i; j < N; j += i) {
        if (d[j] == -1) {
          d[j] = i;
        }
      }
    }
  }
  s[1] = 1;
  for (int i = 2; i < N; i++) {
    if (d[i] == -1) {
      d[i] = i;
      s[i] = i + 1;
    } else {
      int j = i;
      s[i] = 1;
      while (j % d[i] == 0) {
        j /= d[i];
        s[i] = s[i] * d[i] + 1;
      }
      s[i] *= s[j];
    }
  }
  fill(ans, ans + N, -1);
  for (int i = N - 1; i > 0; i--) {
    if (s[i] < N) {
      ans[s[i]] = i;
    }
  }
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    int c;
    cin >> c;
    cout << ans[c] << endl;
  }
  return 0;
}

Full text and comments »

Tutorial of Codeforces Round 713 (Div. 3)

Supermagzzz
4 years ago
200

Codeforces Round #710 (Div. 3)

By Supermagzzz, 4 years ago, translation, In English

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #710 (Div. 3) will start at Mar/25/2021 17:35 (Moscow time). You will be offered 7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 7 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as trusted participants of the third division, you must:

take part in at least two rated rounds (and solve at least one problem in each of them),
do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented by MikeMirzayanov, Supermagzzz, Stepavly and sodafago.

Thanks to darkkcyan, bugdone, harlequen, iankury, bfs.07, songsinger, infinitepro, sodafago, Gassa, Rox, sharepoLOVEDDD for testing this round.

Thanks to MikeMirzayanov for platforms and coordination of our work. Good luck!

</almost-copy-pasted-part>

UDP: Editorial is ready

Full text and comments »

Announcement of Codeforces Round 710 (Div. 3)

+340

Supermagzzz
4 years ago
204

Codeforces Round #702 (Div. 3)

By Supermagzzz, 4 years ago, translation, In English

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #702 (Div. 3) will start at Feb/16/2021 17:35 (Moscow time). You will be offered 7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 7 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

take part in at least two rated rounds (and solve at least one problem in each of them),
do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented by MikeMirzayanov, Supermagzzz, Stepavly and sodafago.

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to darkkcyan, Sho, sodafago, budalnik, kocko, akagami_no_shanks, Gassa, infinitepro, bfs.07 for help in round preparation and testing the round.

Good luck!

</almost-copy-pasted-part>

UPD: Editorial is ready!

Full text and comments »

Announcement of Codeforces Round 702 (Div. 3)

+238

Supermagzzz
4 years ago
168

Codeforces Round #697 (Div. 3)

By Supermagzzz, 4 years ago, translation, In English

Hello, Codeforces! Were you afraid of the lack of contests? We also!

Unfortunately, due to technical problems, the round is declared unrated. You can continue to solve problems, but the results of the current round will not affect your rating. We are sorry for this situation.

<almost-copy-pasted-part>

Hello! Codeforces Round #697 (Div. 3) will start at Jan/25/2021 18:00 (Moscow time). You will be offered 7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 7 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

take part in at least two rated rounds (and solve at least one problem in each of them),
do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented by MikeMirzayanov and prepared by me Supermagzzz and Stepavly

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to darkkcyan, Tzak, bfs.07, songsinger, iankury, spookywooky, Programmer, sodafago, infinitepro for help in round preparation and testing the round.

Good luck!

</almost-copy-pasted-part>

UPD: Editorial is ready!

Full text and comments »

Announcement of Codeforces Round 697 (Div. 3)

+244

Supermagzzz
4 years ago
535

Codeforces Round #693 (Div. 3) Editorial

By Supermagzzz, history, 4 years ago, translation, In English

All problems were invented MikeMirzayanov and developed by me Supermagzzz and Stepavly.

1472A - Cards for Friends

Editorial

Solution

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void solve() {
  int w, h, n;
  cin >> w >> h >> n;
  int res = 1;
  while (w % 2 == 0) {
    w /= 2;
    res *= 2;
  }
  while (h % 2 == 0) {
    h /= 2;
    res *= 2;
  }
  cout << (res >= n ? "YES\n" : "NO\n");
}

int main() {
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
}

1472B - Fair Division

Editorial

Solution

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void solve() {
  int n;
  cin >> n;
  int cnt1 = 0, cnt2 = 0;
  for (int i = 0; i < n; i++) {
    int c;
    cin >> c;
    if (c == 1) {
      cnt1++;
    } else {
      cnt2++;
    }
  }
  if ((cnt1 + 2 * cnt2) % 2 != 0) {
    cout << "NO\n";
  } else {
    int sum = (cnt1 + 2 * cnt2) / 2;
    if (sum % 2 == 0 || (sum % 2 == 1 && cnt1 != 0)) {
      cout << "YES\n";
    } else {
      cout << "NO\n";
    }
  }
}

int main() {
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
}

1472C - Long Jumps

Editorial

Solution

#include <bits/stdc++.h>
using namespace std;

void solve() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int &x : a) {
    cin >> x;
  }

  vector<int> dp(n);
  for (int i = n - 1; i >= 0; i--) {
    dp[i] = a[i];
    int j = i + a[i];
    if (j < n) {
      dp[i] += dp[j];
    }
  }
  cout << *max_element(dp.begin(), dp.end()) << endl;
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

1472D - Even-Odd Game

Editorial

Solution

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void solve() {
  int n;
  cin >> n;
  vector<int> v(n);
  for (int &e : v) {
    cin >> e;
  }
  sort(v.rbegin(), v.rend());
  ll ans = 0;
  for (int i = 0; i < n; i++) {
    if (i % 2 == 0) {
      if (v[i] % 2 == 0) {
        ans += v[i];
      }
    } else {
      if (v[i] % 2 == 1) {
        ans -= v[i];
      }
    }
  }
  if (ans == 0) {
    cout << "Tie\n";
  } else if (ans > 0) {
    cout << "Alice\n";
  } else {
    cout << "Bob\n";
  }
}

int main() {
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}

1472E - Correct Placement

Editorial

Solution

#include <bits/stdc++.h>
using namespace std;

using pii = pair<int, int>;

struct man {
  int h, w, id;
};

bool operator<(const man &a, const man &b) {
  return tie(a.h, a.w, a.id) < tie(b.h, b.w, b.id);
}

struct my_min {
  pii mn1, mn2;
};

vector<pair<int, my_min>> createPrefMins(const vector<man>& a) {
  vector<pair<int, my_min>> prefMin;
  my_min curMin{pii(INT_MAX, -1), pii(INT_MAX, -1)};
  for (auto x : a) {
    if (x.w < curMin.mn1.first) {
      curMin.mn2 = curMin.mn1;
      curMin.mn1 = pii(x.w, x.id);
    } else {
      curMin.mn2 = min(curMin.mn2, pii(x.w, x.id));
    }
    prefMin.emplace_back(x.h, curMin);
  }
  return prefMin;
}

int findAny(const vector<pair<int, my_min>> &mins, int h, int w, int id) {
  int l = -1, r = (int) mins.size();
  while (r - l > 1) {
    int m = (l + r) / 2;
    if (mins[m].first < h) {
      l = m;
    } else {
      r = m;
    }
  }
  if (l == -1) {
    return -1;
  }

  auto mn1 = mins[l].second.mn1;
  auto mn2 = mins[l].second.mn2;
  if (mn1.second != id) {
    return mn1.first < w ? mn1.second + 1 : -1;
  }
  return mn2.first < w ? mn2.second + 1 : -1;
}

void solve() {
  int n;
  cin >> n;
  vector<man> hor, ver;
  vector<pii> a;
  for (int i = 0; i < n; i++) {
    int h, w;
    cin >> h >> w;
    hor.push_back({h, w, i});
    ver.push_back({w, h, i});
    a.emplace_back(h, w);
  }

  sort(hor.begin(), hor.end());
  sort(ver.begin(), ver.end());

  auto horMins = createPrefMins(hor);
  auto verMins = createPrefMins(ver);

  for (int i = 0; i < n; i++) {
    auto[h, w] = a[i];
    int id = findAny(horMins, h, w, i);
    if (id == -1) {
      id = findAny(verMins, h, w, i);
    }
    cout << id << " ";
  }
  cout << endl;
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

1472F - New Year's Puzzle

Editorial

Solution

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void solve() {
  int n, m;
  cin >> n >> m;
  map<int, int> v;
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    v[y] |= (1 << (x - 1));
  }
  const int FULL = 3;
  v[2e9] = FULL;
  int hasLast = 0, lastColor = 0;
  for (auto[x, mask] : v) {
    if (mask != FULL && hasLast) {
      int color = (x + mask) % 2;
      if (lastColor == color) {
        cout << "NO\n";
        return;
      } else {
        hasLast = false;
      }
    } else if (mask == FULL && hasLast) {
        cout << "NO\n";
        return;
    } else if (mask != FULL) {
      lastColor = (x + mask) % 2;
      hasLast = true;
    }
  }
  cout << "YES\n";
}

int main() {
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}

1472G - Moving to the Capital

Editorial

Solution

#include <bits/stdc++.h>
using namespace std;

vector<int> calcDist(vector<vector<int>> const &g) {
  vector<int> dist(g.size(), -1);
  dist[1] = 0;
  queue<int> pq;
  pq.push(1);
  while (!pq.empty()) {
    int u = pq.front();
    pq.pop();
    for (int v : g[u]) {
      if (dist[v] == -1) {
        dist[v] = dist[u] + 1;
        pq.push(v);
      }
    }
  }

  return dist;
}

void dfs(int u, vector<vector<int>> const &g, vector<int> const &dist, vector<int> &dp, vector<bool> &used) {
  used[u] = true;
  dp[u] = dist[u];
  for (int v : g[u]) {
    if (!used[v] && dist[u] < dist[v]) {
      dfs(v, g, dist, dp, used);
    }

    if (dist[u] < dist[v]) {
      dp[u] = min(dp[u], dp[v]);
    } else {
      dp[u] = min(dp[u], dist[v]);
    }
  }
}

void solve() {
  int n, m;
  cin >> n >> m;
  vector<vector<int>> g(n + 1);
  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    g[u].push_back(v);
  }

  vector<int> dist = calcDist(g);
  vector<int> dp(n + 1);
  vector<bool> used(n + 1);
  dfs(1, g, dist, dp, used);
  for (int i = 1; i <= n; i++) {
    cout << dp[i] << " ";
  }
  cout << endl;
}

int main() {
  int tests;
  cin >> tests;
  while (tests-- > 0) {
    solve();
  }
  return 0;
}

Full text and comments »

Tutorial of Codeforces Round 693 (Div. 3)

+147

Supermagzzz
4 years ago
222

Codeforces Round #690 (Div. 3)

By Supermagzzz, history, 4 years ago, translation, In English

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #690 (Div. 3) will start at Dec/15/2020 17:35 (Moscow time). You will be offered 6 problems (one of them is split into two subtasks) with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

take part in at least two rated rounds (and solve at least one problem in each of them),
do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented by MikeMirzayanov and prepared by me Supermagzzz and Stepavly

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to Sho, kocko, brian, Crazy_hedgehog, manta1130, Rox, Gassa for help in round preparation and testing the round.

Good luck!

</almost-copy-pasted-part>

UPD: Editorial is published

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Announcement of Codeforces Round 690 (Div. 3)

+475

Supermagzzz
4 years ago
244

Codeforces Round #650 (Div. 3) Editorial

By Supermagzzz, history, 5 years ago, translation, In English

All problems were developed by me Supermagzzz and Stepavly.

1367A - Short Substrings

Author: MikeMirzayanov

Editorial

Solution

#include <bits/stdc++.h>
using namespace std;

int main() {
	int t;
	cin >> t;

	for (int test = 1; test <= t; test++) {
		string b;
		cin >> b;

		string a = b.substr(0, 2);

		for (int i = 3; i < b.size(); i += 2) {
			a += b[i];
		}

		cout << a << endl;
	}

	return 0;
}

1367B - Even Array

Авторы: Supermagzzz, Stepavly

Editorial

Solution

#include <bits/stdc++.h>

using namespace std;
using ld = long double;
using ll = long long;

void solve() {
    int n;
    cin >> n;
    int a = 0, b = 0;
    for (int i = 0; i < n; i++) {
        int x;
        cin >> x;
        if (x % 2 != i % 2) {
            if (i % 2 == 0) {
                a++;
            } else {
                b++;
            }
        }
    }
    if (a != b) {
        cout << -1 << endl;
    } else {
        cout << a << endl;
    }
}

int main() {
    int n;
    cin >> n;
    while (n--) {
        solve();
    }
}

1367C - Social Distance

Авторы: Supermagzzz, Stepavly

Editorial

Solution

#include <bits/stdc++.h>
using namespace std;

int main() {
	int t;
	cin >> t;

	for (int test = 1; test <= t; test++) {
		int n, k;
		cin >> n >> k;
		string s;
		cin >> s;

		int res = 0;

		for (int i = 0; i < n;) {
			int j = i + 1;

			for (; j < n && s[j] != '1'; j++);

			int left = s[i] == '1' ? k : 0;
			int right = j < n && s[j] == '1' ? k : 0;
			int len = j - i;

			if (left == k) {
				len--;
			}

			len -= left + right;

			if (len > 0) {
				res += (len + k) / (k + 1);
			}

			i = j;
		}

		cout << res << endl;
	}

	return 0;
}

1367D - Task On The Board Автор: MikeMirzayanov

Editorial

Solution

#include <bits/stdc++.h>

using namespace std;

#define forn(i, n) for (int i = 0; i < int(n); i++)

int main() {
    int q;
    cin >> q;
    forn(qq, q) {
        string s;
        cin >> s;
        int n;
        cin >> n;
        vector<int> b(n);
        forn(i, n)
            cin >> b[i];
        vector<vector<int>> groups;
        while (true) {
            vector<int> pos;
            forn(i, n)
                if (b[i] == 0)
                    pos.push_back(i);
            if (pos.empty())
                break;
            groups.push_back(pos);
            forn(i, n)
                if (b[i] == 0)
                    b[i] = INT_MAX;
                else
                    for (int pp: pos)
                        b[i] -= abs(i - pp);
        }
        map<char, int> cnts;
        forn(i, s.size())
            cnts[s[i]]++;
        auto j = cnts.rbegin();
        string t(n, '?');
        for (auto g: groups) {
            while (j->second < g.size())
                j++;
            for (int pp: g)
                t[pp] = j->first;
            j++;
        }
        cout << t << endl;
    }
}

1367E - Necklace Assembly

Автор: MikeMirzayanov

Editorial

Solution

#include <bits/stdc++.h>
using namespace std;

int main() {
	int test;
	cin >> test;

	while (test--) {
		int n, k;
		cin >> n >> k;
		string s;
		cin >> s;

		vector<int> cnt(26);

		for (char c : s) {
			cnt[c - 'a']++;
		}

		for (int len = n; len >= 1; len--) {
			vector<bool> used(len);
			vector<int> cycles;

			for (int i = 0; i < len; i++) {
				if (used[i]) {
					continue;
				}

				int j = (i + k) % len;
				used[i] = true;
				cycles.push_back(0);
				cycles.back()++;

				while (!used[j]) {
					cycles.back()++;
					used[j] = true;
					j = (j + k) % len;
				}
			}

			vector<int> cur_cnt(cnt);

			sort(cycles.begin(), cycles.end());
			sort(cur_cnt.begin(), cur_cnt.end());

			bool can_fill = true;

			while (!cycles.empty()) {
				if (cur_cnt.back() < cycles.back()) {
					can_fill = false;
					break;
				} else {
					cur_cnt.back() -= cycles.back();
					cycles.pop_back();
					sort(cur_cnt.begin(), cur_cnt.end());
				}
			}

			if (can_fill) {
				cout << len << endl;
				break;
			}
		}
	}
}

1367F2 - Flying Sort (Hard Version)

Автор: MikeMirzayanov Stepavly Supermagzzz

Editorial

Solution

#include <bits/stdc++.h>

using namespace std;
using ld = long double;
using ll = long long;

void solve() {
    int n;
    cin >> n;
    vector<int> v(n);
    vector<pair<int, int>> a(n);
    for (int i = 0; i < n; i++) {
        cin >> v[i];
        a[i] = {v[i], i};
    }
    sort(a.begin(), a.end());
    vector<int> p(n);
    int j = 0;
    unordered_multiset<int> next;
    for (int i = 0; i < n; i++) {
        if (i > 0 && a[i].first != a[i - 1].first) {
            j++;
        }
        p[a[i].second] = j;
        next.insert(j);
    }
    unordered_map<int, int> d;
    vector<int> dp1(n), dp2(n), dp3(n), cnt(n);
    for (int i = 0; i < n; i++) {
        if (next.count(p[i])) {
            next.erase(next.find(p[i]));
        }
        if (d.count(p[i] - 1)) {
            if (!d.count(p[i])) {
                dp2[i] = max(dp2[i], dp1[d[p[i] - 1]] + 1);
                if (!next.count(p[i] - 1)) {
                    dp2[i] = max(dp2[i], dp2[d[p[i] - 1]] + 1);
                }
            }
            if (!next.count(p[i] - 1)) {
                dp3[i] = max(dp3[i], dp2[d[p[i] - 1]] + 1);
            }
            dp3[i] = max(dp3[i], dp1[d[p[i] - 1]] + 1);
        }
        if (d.count(p[i])) {
            dp3[i] = max(dp3[i], dp3[d[p[i]]] + 1);
            dp2[i] = max(dp2[i], dp2[d[p[i]]] + 1);
            dp1[i] = dp1[d[p[i]]] + 1;
        } else {
            dp1[i] = 1;
        }
        dp2[i] = max(dp2[i], dp1[i]);
        dp3[i] = max(dp3[i], dp2[i]);
        d[p[i]] = i;
    }
    cout << n - *max_element(dp3.begin(), dp3.end()) << "\n";
}

int main() {
    int n;
    cin >> n;
    while (n--) {
        solve();
    }
}

Full text and comments »

Tutorial of Codeforces Round 650 (Div. 3)

Supermagzzz
5 years ago
280

Codeforces Round #644 (Div. 3)

By Supermagzzz, history, 5 years ago, translation, In English

Hello, Codeforces!

We have planned this round as a Div. 4, but testing showed us, that problems are more suitable for Div. 3. Therefore, instead of the previously announced Div. 4 we will hold Div. 3 round.

<almost-copy-pasted-part>

Hello! Codeforces Round #644 (Div. 3) will start at May/24/2020 16:35 (Moscow time). You will be offered 8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 8 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

take part in at least two rated rounds (and solve at least one problem in each of them),
do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented by MikeMirzayanov and prepared by me and Stepavly

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to antontrygubO_o, iankury, bfs.07, kocko, Ilya-bar, arsijo, pashka, Gassa, neal, vovuh for help in round preparation and testing the round.

Good luck!

</almost-copy-pasted-part>

UPD: Editorial is out

Full text and comments »

Announcement of Codeforces Round 644 (Div. 3)

+348

Supermagzzz
5 years ago
238

Codeforces Round #603 (Div. 2)

By Supermagzzz, history, 5 years ago, In English

Hello Codeforces!

We, Supermagzzz, Stepavly, AdvancerMan, unreal.eugene, are ITMO students, who want to contribute to Codeforces community, went to MikeMirzayanov and offered him to help with rounds testing. But MikeMirzayanov invited us to create our own round with his help. And now...

We're glad to invite you to Codeforces Round #603 (Div. 2), which will be held on Nov/29/2019 17:35 (Moscow time). It will be rated for all participants with a rating below 2100. You will be given six problems and two hours to solve them.

The problems were invented and prepared by Supermagzzz, Stepavly, AdvancerMan, unreal.eugene, MikeMirzayanov.

Special thanks to:

VArtem, budalnik, arsijo, Alexxx, MeowMr, Vinatorul, SpeedOfMagic, RDmitriyS, Rox, Mr.Hakimov for testing this round and giving good advices about the problemset.

MikeMirzayanov for great systems Codeforces and Polygon and coordinating round preparation.

UPD: Scoring: 500 — 1250 — 1250 — 1750 — 2500 — 3000

We hope you will enjoy the problems. Good luck, wish you a high rating!

UPD1.5: Thanks for participating! Congratulations to the winners!

Top 5 Div. 2:

Top 5 Div. 2 + unoffical:

UPD2: Editorial is out!

Full text and comments »

Announcement of Codeforces Round 603 (Div. 2)

+325

Supermagzzz
5 years ago
237