Hello, Codeforces friends!

I'd like to invite you to the mirror of the UP ACM Algolympics 2023 Final Round. Algolympics is an annual contest organized by the Association for Computing Machinery, University of the Philippines Diliman Chapter. It is open to teams consisting of undergraduate college students from the Philippines. This year's contest was held on March 25, 2023, but the mirrors are open to everyone!

Contest details:

• There are 13 problems over 5 hours.
• Every problem is worth 1 point.
• Scoring is binary. There are no partial points.
• The penalties are ICPC-style.
• The mirror will be held on June 17, 2023, from 9:00am to 2:00pm (UTC+8).
• Click here to go to the gym contest

Please register at the gym to join the mirror.

The problems range from easy to challenging. Everyone from the newbie to the grandmaster should find an interesting problem in the contest.

The problem setters are myself, Cisco Ortega (Shisuko), Josh Quinto (1NCID3R) and some of his colleagues in Samsung Research. Thanks to MikeMirzayanov for Codeforces and Polygon!

Links to the mirrors! day 1, day 2 (Please register at the gym)

Hello Codeforces!

I'd like to invite you to the mirrors of the 2020 final rounds of the National Olympiad in Informatics – Philippines. The mirrors will be held in the Codeforces gym. The NOI.PH is the Philippines' qualifier for the IOI.

Contest format:

• There are 2 contest days.
• There are 5 problems over 5 hours, per day.
• The problems will have subtasks. The maximum score for each problem will be 100 points.
• Some problems may have special scoring rules which will be indicated in the statement.
• The submission that achieves the maximum score is counted towards the final ranking.
• The problems range from easy to hard. We also tried to cover a diverse set of topics.
• Editorials will be released after the mirror contests end.
• Day 1 mirror: August 15, 2020 4pm UTC+8 (8am UTC) to 9pm UTC+8 (1pm UTC)
• Day 2 mirror: August 16, 2020 4pm UTC+8 (8am UTC) to 9pm UTC+8 (1pm UTC)

Acknowledgments: The problem setters were 1NCID3R, andrewting, cjquines, guissmo, Shisuko, timd, verngutz and myself (kevinsogo). Thanks to jddantes, jvafable, TheLostCookie, Marte for testing. Lastly, thanks to MikeMirzayanov for Codeforces and Polygon.

Have fun!

Edit: The registration is now open for Day 1!

To those planning to participate, please ensure that you have installed Java JDK version at least 8. Knowing how to program in Java is not needed, but some tasks will ask you to run Java programs.

Edit: The editorials have been released.

• Day 1
• Day 2

Enjoy!

Hello, Codeforces community!

I'd like to invite you to the mirrors of the UP ACM Algolympics 2020 Elimination and Final Rounds. Algolympics is an annual contest organized by the Association for Computing Machinery, University of the Philippines Chapter, held onsite at the University of the Philippines Diliman. It is open to teams consisting of undergraduate college students from the Philippines.

The mirrors are open to everyone!

Elimination Round Mirror

• There are 18 problems over several days.
• Every problem is worth 1 point.
• Scoring is binary. There are no partial points.
• The penalty is the latest submission for an eventually solved problem.
• The mirror will be held on February 27, 2020 (12:00pm UTC+8) — March 1, 2020 (6:00am UTC+8).
• Gym contest

Final Round Mirror

• There are 13 problems over 5 hours.
• Every problem is worth 1 point.
• Scoring is binary. There are no partial points.
• The penalty is ICPC-styled.
• The mirror will be held on March 1, 2020, from 1:00pm to 6:00pm (both UTC+8).
• Gym contest

Please register at the gym to join the mirrors.

The rounds were originally held on January 17-27, 2020 (online) and February 22, 2020 (onsite, at UP Diliman), respectively.

The problems range from easy to challenging. Everyone from the newbie to the grandmaster will find an interesting problem in the contest. The Elimination Round will contain standard problems, while the Final Round will contain more original and interesting problems, and is harder on average.

Editorials will be released after the mirror contests end.

Acknowledgments: The problem setters are Kevin Atienza (kevinsogo), Josh Quinto (1NCID3R), JD Dantes (jddantes), Payton Yao (jabbawookiees), Tim Dumol (timd), Patrick Celon (Celon), Pio Fortuno III (sasarpillsa), Barbara David (chocochocobed), and Philip Zuniga. Thanks to Anton Rufino (antonrufino), Williard Jose (williard), Marc San Pedro (MDSP) and Alvin Burgos (ajmburgos09) for additional help in testing. Lastly, thanks to MikeMirzayanov for Codeforces and Polygon!

Edit: Thanks for joining the Elimination Round mirror! I hope you enjoyed it.

You can access the editorials for the Elimination Round by clicking here. The link to the judges' accepted programs can also be found in the editorial document. (Read the introductory paragraph.) Feel free to ask questions about the problems/solutions in the comments.

Edit: Thanks for joining the Final Round mirror! I hope you enjoyed the round!

You can access the editorials for the Final Round by clicking here. Feel free to ask questions about the problems/solutions in the comments.

See you next time!

Link to the mirror! (Please register at the gym)

Hello Codeforces!

I'd like to invite you to the mirror of the 2020 eliminations round of the National Olympiad in Informatics – Philippines. The mirror will be held in the Codeforces gym. The NOI.PH is the Philippines' qualifier for the IOI.

Contest format:

• There are 17 problems over 9 days.
• The problems will have subtasks. The maximum score for each problem will be 100 points.
• The submission that achieves the maximum score is counted towards the final ranking.
• The problems range from easy to challenging. Everyone from the newbie to the grandmaster will find an interesting problem in the contest.

Editorials will be released after the mirror contest ends.

Acknowledgments: The problem setters were kevinsogo, cjquines, Shisuko, andrewting, jabbawookiees, guissmo, verngutz. Thanks to Benq and ekzhang for additional help in testing. Lastly, thanks to MikeMirzayanov for Codeforces, and Polygon, which was used to prepare the problems.

Edit: Registration is now open! I've added the mirror link. Please register at the gym.

Have fun!

Edit: Thanks for joining the mirror. Congratulations to TLE for winning the mirror!

Congratulations to the top five:

• TLE
• briansu
• baluteshih
• yogahmad77
• baIuteshih

Please wait for a bit until we release the official editorials and solution analyses. Meanwhile, feel free to comment here about the problems.

Edit: The editorials have been released. Click here. Enjoy!

We apologize for the delay. Anyway, once you see the document, I hope you'll understand that it took a long time to prepare given the amount of detail our editorialists usually aim for.

I hope you enjoyed the problems! Thanks to the onsite teams and coaches who gave feedback; I'm glad the reception was positive.

Interestingly, in the onsite ICPC round, while "Kirchhoff" got several accepted solutions, "Miss Punyverse" got no accepted submissions at all! It is the reverse here. (Kirchhoff even has a trickier output format in the onsite round compared to the version presented in Codeforces.) It seems the ICPC scoreboard really affects the results greatly; what the top few teams are working on influences what everyone else will be working on.

I am planning on releasing the full, untouched ICPC Manila 2019 problem set in the gym sometime in the future, so you can see which problems you missed. The Intergalactic Sliding Puzzle is not the hardest problem in the round!

1281A - Suffix Three

for cas in range(int(input())): print({'o': "FILIPINO", 'a': "KOREAN", 'u': "JAPANESE"}[input()[-1]])

Accepted Submission: 67015948

1281B - Azamon Web Services

def solve(s, t):
    mns = list(s)
    for i in range(len(s)-2,-1,-1): mns[i] = min(mns[i], mns[i + 1])
    for i in range(len(s)):
        if s[i] != mns[i]:
            j = max(j for j, v in enumerate(s[i:], i) if v == mns[i])
            s = s[:i] + s[j] + s[i+1:j] + s[i] + s[j+1:]
            break
    return s if s < t else '---'

for cas in range(int(input())):
    print(solve(*input().split()))

Accepted Submission: 67049609

1281C - Cut and Paste

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll mod = 1'000'000'007; //'
constexpr int N = 1111;

char _s[N];
ll solve() {
    int x;
    scanf("%d%s", &x, _s);
    ll ls = strlen(_s);
    vector<char> s(_s, _s + ls);
    for (int i = 1; i <= x; i++) {
        int v = s[i - 1] - '1';
        if (s.size() < x) {
            vector<char> sub(s.begin() + i, s.end());
            for (int it = 0; it < v; it++) s.insert(s.end(), sub.begin(), sub.end());
        }
        ls = (ls + (ls - i) * v) % mod;
    }
    return ls;
}


int main() {
    int z;
    for (scanf("%d", &z); z--; printf("%lld\n", (solve() % mod + mod) % mod));
}

Accepted Submission: 67016113

1281D - Beingawesomeism

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

int solve(int r, int c, vector<string> grid) {
    vector<int> rows(r), cols(c);
    int total = 0;
    for (int i = 0; i < r; i++) {
        for (int j = 0; j < c; j++) {
            if (grid[i][j] == 'A') rows[i]++, cols[j]++, total++;
        }
    }
    if (total == r * c) return 0;
    if (total == 0) return -1;

    if (rows[0] == c || rows.back() == c || cols[0] == r || cols.back() == r) return 1;
    if (grid[0][0] == 'A' || grid[0].back() == 'A' || grid.back()[0] == 'A' || grid.back().back() == 'A') return 2;
    if (*max_element(rows.begin(), rows.end()) == c || *max_element(cols.begin(), cols.end()) == r) return 2;
    if (rows[0] || rows.back() || cols[0] || cols.back()) return 3;
    return 4;
}

int main() {
    int z;
    for (cin >> z; z--;) {
        int r, c;
        cin >> r >> c;
        vector<string> grid(r);
        for (int i = 0; i < r; i++) cin >> grid[i];
        int res = solve(r, c, grid);
        (~res ? cout << res : cout << "MORTAL") << '\n';
    }
}

Accepted Submission: 67016167

1281E - Jeremy Bearimy

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

void solve() {
    int n;
    cin >> n;
    n <<= 1;
    vector<vector<pair<int,ll>>> adj(n);
    for (int i = 0; i < n - 1; i++) {
        int a, b; ll c;
        cin >> a >> b >> c;
        a--, b--;
        adj[a].emplace_back(b, c);
        adj[b].emplace_back(a, c);
    }

    vector<int> parent(n, -1), que(1, 0);
    vector<ll> parent_cost(n);
    parent[0] = 0;
    for (int f = 0; f < que.size(); f++) {
        int i = que[f];
        for (auto [j, c]: adj[i]) {
            if (parent[j] == -1) {
                parent[j] = i;
                parent_cost[j] = c;
                que.push_back(j);
            }
        }
    }
    vector<int> size(n, 1);
    ll mn = 0, mx = 0;
    reverse(que.begin(), que.end());
    for (int i : que) {
        size[parent[i]] += size[i];
        mx += parent_cost[i] * min(size[i], n - size[i]);
        mn += parent_cost[i] * (size[i] & 1);
    }
    cout << mn << " " << mx << '\n';
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int z;
    for (cin >> z; z--; solve());
}

Accepted Submission: 67020743

1281F - Miss Punyverse

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

struct Group {
    int win; ll adv;
    Group(int win = -1, ll adv = 0): win(win), adv(adv) {}
    Group operator+(const Group& o) const {
        return Group(win + o.win, adv + o.adv);
    }
    Group operator+() const {
        return Group(win + (adv > 0));
    }
    bool operator<(const Group& o) const {
        return win < o.win || win == o.win && adv < o.adv;
    }
};

vector<Group> convolve(const vector<Group>& fa, const vector<Group>& fb) {
    vector<Group> fi(fa.size() + fb.size());
    for (int a = 0; a < fa.size(); a++) {
        for (int b = 0; b < fb.size(); b++) {
            fi[a + b    ] = max(fi[a + b    ], fa[a] +  fb[b]);
            fi[a + b + 1] = max(fi[a + b + 1], fa[a] + +fb[b]);
        }
    }
    return fi;
}

vector<vector<Group>> f;
vector<vector<int>> adj;
void convolve_tree(int i, int p = -1) {
    for (int j : adj[i]) {
        if (j == p) continue;
        convolve_tree(j, i);
        f[i] = convolve(f[i], f[j]);
    }
}

int solve() {
    int n, m;
    scanf("%d%d", &n, &m);
    f = vector<vector<Group>>(n, vector<Group>(1, Group(0)));
    for (int i = 0, b; i < n; i++) {
        scanf("%d", &b);
        f[i][0].adv -= b;
    }
    for (int i = 0, w; i < n; i++) {
        scanf("%d", &w);
        f[i][0].adv += w;
    }
    adj = vector<vector<int>>(n);
    for (int i = 1; i < n; i++) {
        int x, y;
        scanf("%d%d", &x, &y);
        x--, y--;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    convolve_tree(0);
    return (+f[0][m - 1]).win;
}

int main() {
    int z;
    for (scanf("%d", &z); z--; printf("%d\n", solve()));
}

Accepted Submission: 67016189

1280E - Kirchhoff's Current Loss

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = 1LL << 60;

class Circuit {
public:
    ll w = -1;
    ll width() {
        if (w == -1) compute_width();
        return w;
    }
    virtual void compute_width() {}
    virtual void assign(ll value) {}
    virtual ostream& write_to(ostream& os) const { return os; }
    void assign_minimal(ll value) { assign(value * width()); }
    friend ostream& operator<<(ostream& os, const Circuit& circuit);
};

ostream& operator<<(ostream& os, const Circuit& circuit) {
    return circuit.write_to(os);
}

class Resistor: public Circuit {
public:
    ll value = -1;
    Resistor() {}
    void compute_width() override {
        w = 1;
    }
    void assign(ll value) override {
        this->value = value;
    }
    ostream& write_to(ostream& os) const override {
        return os << ' ' << value;
    }
};

class Join: public Circuit {
public:
    char typ;
    vector<Circuit*> children;
    Join() {}
    void compute_width() override {
        w = typ == 'S' ? INF : 0;
        for (auto child: children) {
            ll ww = child->width();
            w = typ == 'S' ? min(w, ww) : w + ww;
        }
    }
    void assign(ll value) override {
        for (auto child: children) {
            if (typ == 'S') {
                if (child->width() == width()) {
                    child->assign(value);
                    value = 0;
                } else {
                    child->assign(0);
                }
            } else {
                child->assign(value);
            }
        }
    }
    ostream& write_to(ostream& os) const override {
        for (auto child: children) os << *child;
        return os;
    }
};

class CircuitParser {
    const string& s;
    int i = 0;
    CircuitParser(const string& s): s(s) {}
    Circuit *parse() {
        if (s[i++] == '(') {
            Join *j = new Join();
            while (true) {
                j->children.push_back(parse());
                if (s[i++] == ')') break;
                j->typ = s[i++];
                i++;
            }
            return j;
        } else {
            return new Resistor();
        }
    }
public:
    static Circuit *parse(const string& s) {
        return CircuitParser(s).parse();
    }
};

void solve(ll a, const string& s) {
    Circuit *c = CircuitParser::parse(s);
    c->assign_minimal(a);
    cout << "REVOLTING" << *c << '\n';
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int z;
    for (cin >> z; z--;) {
        ll a;
        string s;
        cin >> a;
        getline(cin, s);
        assert(s[0] == ' ');
        solve(a, s.substr(1));
    }
}

Accepted Submission: 67016199

1280F - Intergalactic Sliding Puzzle

def solve(k, grid):
    seek = *range(2*k + 2), *range(4*k + 1, 2*k + 1, -1)
    flat = [seek[v] for v in grid[0] + grid[1][::-1] if v]

    m = {
        'L': 'l'*2*k + 'u' + 'r'*2*k + 'd',
        'R': 'u' + 'l'*2*k + 'd' + 'r'*2*k,
        'C': 'l'*k + 'u' + 'r'*k + 'd',
        'D': 'CC' + 'R'*(2*k + 1) + 'CC' + 'R'*(2*k + 2),
        'F': 'R'*(k - 1) + 'DD' + 'R'*(2*k + 1) + 'D' + 'L'*2*k + 'DD' + 'L'*k,
        'G': 'FF',
    }

    [(i, j)] = [(i, j) for i in range(2) for j in range(2*k + 1) if grid[i][j] == 0]
    st = 'r'*(2*k - j) + 'd'*(1 - i)

    for v in range(2, 4*k + 2):
        ct = flat.index(v)

        if ct >= 2:
            st += 'L'*(ct - 2) + 'GR'*(ct - 2) + 'G'
            flat = flat[ct - 1: ct + 1] + flat[:ct - 1] + flat[ct + 1:]

        if ct >= 1:
            st += 'G'
            flat = flat[1:3] + flat[:1] + flat[3:]

        st += 'L'
        flat = flat[1:] + flat[:1]
        
    if flat[0] == 1: return st, m

def main():
    def get_line():
        return [0 if x == 'E' else int(x) for x in input().split()]

    for cas in range(int(input())):
        res = solve(int(input()), [get_line() for i in range(2)])
        if res is None:
            print('SURGERY FAILED')
        else:
            print('SURGERY COMPLETE')
            st, m = res
            print(st)
            for shortcut in m.items(): print(*shortcut)
            print('DONE')

main()

Accepted Submission: 67026155

Hello, Codeforces community!

I'm glad to invite you to Codeforces Round 607 (Div. 1) and Codeforces Round 607 (Div. 2), which will be held on Dec/15/2019 08:05 (Moscow time). The round will be rated for both divisions.

The problems were taken (mostly) from the 2019 ICPC Asia-Manila Regional Contest that's happening at the same time. Thus, they have been prepared by various setters and testers from the Philippines: myself (kevinsogo), Kyle See (kylesky), Payton Yao (jabbawookiees), Tim Dumol (timd), Guissmo Asuncion (guissmo in HackerRank) and Marte Soliza (myrtactle in TopCoder).

Since the problems are based on the ICPC Manila regionals, we request all the coaches onsite to refrain from making the problem set public. We also request the coaches and everyone else who has seen the problems (or part of it) to refrain from joining this round.

A huge thanks to isaf27 for coordinating and helping me set up this round. Thanks to 300iq for some testing. Of course, thanks as well to MikeMirzayanov for providing us Codeforces and Polygon. These are great gifts to the competitive programming community! Also, thanks for the opportunity to use our problem set for a CF round.

You will be given 6 problems in both divisions and 2 hours to solve them. I recommend reading all the problems; they were written by talented writers from the judging team.

Good luck, have fun, and I wish everyone high ratings!

The scoring distribution will be announced closer to the beginning of the round.

Update: The scoring will be as follows:

Div.2: 500 — 1250 — 1500 — 2000 — 2500 — 3000
Div.1: 500 — 1000 — 1500 — 1750 — 2250 — 3000

Good luck and have fun!

Update: The editorial is up: Click here.

Congratulations to the winners! Congratulations to ksun48 for winning the Div. 1 round, and I_am_single for winning the Div. 2 round!

Div. 1 Winners:

1. ksun48
2. Um_nik
3. ecnerwala
4. VivaciousAubergine
5. Radewoosh

Div. 2 Winners:

1. I_am_single
2. RikukiIX
3. Owen_codeisking
4. ly_61
5. p6pou

I hope you enjoyed the problems! Thanks to the onsite teams and coaches who gave feedback; I'm glad the reception was positive.

I am planning on releasing the full, untouched ICPC Manila 2019 problem set in the gym sometime in the future, so you can see which problems you missed. The Intergalactic Sliding Puzzle is not the hardest problem in the round!

Hello, CodeForces Community!

HackerRank's Week of Code 38 is starting today, June 18th 7:00am UTC.

Each day, from Monday to Saturday, we'll unlock a new challenge for you to solve. The contest is rated and the top 10 hackers will win HackerRank T-shirts.

The maximum score for each problem decreases by 10% at the end of every 24 hours. Also, your submissions will run on hidden test cases at the end of every 24 hours.

The contest problems are written and tested by kevinsogo, koca_kodza, ashmelev, saurabh42, VastoLorde95, nonsequitur, shashank21j, zemen, pkacprzak, boleyn.su, niyaznigmatul. (I assume these people use the same CF and HR handles.)

Good luck and happy coding!

Hello Codeforces Community!

I invite you all to join HackerRank's HourRank 28 on June 3, 2018, at 20:30 IST.

You will be given one hour to solve three tasks. The contest will be rated and the top ten contestants will receive HackerRank T-shirts!

The problems are created by mr.logix, abx_2109, and coderdecode1 and tested by me.

Good luck and happy coding!

Hello Codeforces Community,

I invite you all to join HackerRank's World Codesprint 13 starting on 26 May 2018. The contest duration is 48 hours.

The winners of the contest will win up to 1000USD cash prizes. Also, there are opportunities to win some nice T-shirts.

The contest will be rated. If two persons get the same score, the person who reached the score first will be ranked higher. There will be 7 algorithmic challenges in the contest.

The problems are prepared by immuntasir, sreka11, pkacprzak, virus_1010, qoo2p5, saluja123, BishalG, Manashi, Baba, adamant, and myself.

Good luck, and I hope you enjoy the problems!

Hello Codeforces Community!

I invite you all to join HackerRank's HourRank 27 on April 2, 2018, at 20:30 IST.

You will be given one hour to solve three tasks. The contest will be rated and the top ten contestants will receive HackerRank T-shirts!

The problems are prepared by guptautkarsh028, svanidz1, pkacprzak, wanbo and myself (kevinsogo). I suggest you read all of them. I hope you'll like them!

Good luck and happy coding! Also, happy April Fools' Day! (This announcement is not an April Fools joke.)

Hello Codeforces Community,

I am glad to share HackerRank's University Codesprint 4 starting on 23rd February 2018. The contest duration is 48 hours.

The winners of the contest will win up to 1000USD cash prizes. The top 100 will also win awesome hoodies. (The winners will be required to give proof that they are currently enrolled in the university they represented during University CodeSprint.)

The contest will be rated. If two person gets the same score, the person who reached the score first will be ranked higher. There will be a separate ranklists for schools.

There will be 7 algorithmic challenges in this contest.

The problems were prepared by Alladdin, prateekg, niyaznigmatul, BishalG, anuj95, wanbo, svanidz1, kevinsogo, xennygrimmato, geek_geek, Wild_Hamster, shashank21j.

Good luck and Happy Coding!

Hello Codeforces Community!

I invite you all to join HackerRank's HourRank 26 on February 2, 2018, at 20:30 IST.

There will be three tasks in the round and one hour for you to solve them. The contest will be rated and the top ten contestants will receive HackerRank T-shirts!

The problems are prepared by different setters and testers: VastoLorde95, Harun, shashank21j, pkacprzak, ikbal and kevinsogo. I suggest you read all of them. I hope you'll like them!

Good luck and happy coding!

Hello Codeforces Community,

I invite you all to join HackerRank's World Codesprint 12 starting on 14 December 2017. The contest duration is 48 hours.

The winners of the contest will win up to 1000USD cash prizes. Also, there are opportunities to win some nice hoodies.

The contest will be rated. If two persons get the same score, the person who reached the score first will be ranked higher. There will be 7 algorithmic challenges in the contest.

The problems are prepared by sreka11, krismaz, nezametdinov, forthright48, muratekici, shashank21j, pkacprzak, Xsquare, danilka.pro, Golovanov399, niyaznigmatul and myself.

Good luck, and I hope you enjoy the problems!

P.S. I hope I got all the CF handles right.

Hello Codeforces Community!

I invite you all to join HackerRank's HourRank 24 on November 2, 2017, at 20:30 IST.

There will be four tasks in the round and one hour for you to solve them. The contest will be rated and the top ten contestants will receive HackerRank T-shirts!

The problems are prepared by anveshi and tested by Stomach_ache, qoo2p5 and me. There are four problems this time instead of three. I suggest you read all of them. I hope you'll like them!

Good luck and Happy Coding!

Hello, Codeforces Community!

I invite you all to join HackerRank's University CodeSprint 3 starting on 29th September 2017. The contest duration is 48 hours.

The winners of the contest will win up to 1000USD cash prizes. The top 100 will also win awesome hoodies. (Winners will be required to give proof that they are currently enrolled in the university they represented during the University CodeSprint.)

The contest will be rated. If two people get the same score, the person who reached the score first will be ranked higher. There will be a separate rank list for schools.

There will be 7 algorithmic challenges in this contest. Some of them will have subtasks, so I highly recommend you to read all of them.

The problems were created by immuntasir, sreka11, svanidz1, sgtlaugh and Hillan and tested by Shafaet, pkacprzak, wanbo, Wild_Hamster and me. Big thanks to Wild_Hamster for helping to review and test most of the problems.

Good luck and happy coding!

Hello Codeforces Community!

I invite you all to join HackerRank's HourRank 23 on September 9, 2017, at 20:30 IST.

There will be three tasks in the round and one hour for you to solve them. The contest will be rated and the top ten contestants will receive HackerRank T-shirts!

The problems are prepared by Wild_Hamster, zoomswk and me, and tested by shashank21j, Birjik and me. I hope you'll like them!

This round is a bit harder than the usual for HourRank. I suggest you read all the problems.

Good luck and Happy Coding!

Hello Codeforces community,

I would like to invite you to join HackerRank's 101 Hack 51 which starts at 1500 UTC, August 7, 2017.

There will be five tasks and three hours for you to solve them. The contest will be rated and the top ten contestants will receive HackerRank T-shirts!

The problems are prepared by Yury Shilyaev (hloya_ygrt) and Vlad Vishnevsky (Vladik). (HackerRank only displays one author per problem, but the whole set was actually prepared by both.) I tested the problems and I found them to be interesting. I hope you'll enjoy the problems as much as I did!

Happy Coding!

Hello Codeforces community,

I would like to invite you to join HackerRank's 101 Hack 50 on June 20, 2017.

There will be five tasks and three hours for you to solve them. The contest will be rated and the top ten contestants will receive HackerRank T-shirts!

The problems are prepared by kevinsogo, nabila_ahmed, zemen, fedimser, and krismaz and tested by shashank21j, allllekssssa, bayleef, wanbo, and kevinsogo. I hope you'll enjoy the problems prepared by the community!

Happy Coding!

Hello CodeForces Community!

I would like to invite you all to the mirror contest of ACM-ICPC Asia — Kolkata Onsite Mirror Contest ACM-ICPC Asia — Kolkata Onsite Mirror Contest. For those who are prepping for the ICPC onsite regionals this would be a perfect platform to practice as it would simulate the real onsite contest.

Contest Details

Time: 27th December 2016 (1100 hrs) to 27th December 2016 (1600 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Contest link: https://www.codechef.com/KOL16MOS

Registration: You just need to register as a Team on CodeChef. Those who are interested and do not have a CodeChef handle are requested to register in order to participate.

Good Luck! Hope to see you participating!!

Note: The mirror contest will run in parallel to the main contest with an hour delay.

Hello CodeForces Community!

Being your Secret Santa this Christmas, I have packed a nice little gift for you. I am happy to invite you to the ACM-ICPC Asia — Kharagpur Onsite Mirror Contest ACM-ICPC Asia — Kharagpur Onsite Mirror Contest. Please do come and open your little gift on 17th December 1000 hours IST.

Joining me on the problem setting panel are:

Problem Testers: Errichto(Kamil Debowski), kingofnumbers(Hasan Jaddouh), kevinsogo(Kevin Charles Atienza)
Problem Setters: PraveenDhinwa(Praveen Dhinwa), Balajiganapathi(Balajiganapathi Senthilnathan), animeshf(Animesh Fatehpuria), arjunarul(Arjun Arul), adurysk(Surya Kiran), kevinsogo(Kevin Charles Atienza).

I hope you will enjoy solving them. Please give your feedback on the problem set in the comments below after the contest. You can find the rest of the details about the contest below.

Time: 17th December 2016 (1000 hrs) to 17th December 2016 (1500 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Details: https://www.codechef.com/KGP16MOS

Registration: You just need to register as a Team on CodeChef. Those who are interested and do not have a CodeChef handle are requested to register in order to participate.

Good Luck! Hope to see you participating!

Hello CodeForces Community!

We are a few hours away from the SnackDown 2016 Finale. The atmosphere here at the Onsite Finale is amazing. All the teams here seem excited for the final contest.

In parallel to the Onsite Finale there will be a mirror contest of the onsite finale and I’d like to invite you to participate in it. The SnackDown Onsite Finale Mirror Contest will begin at 12:00 PM, 9 th July.

For the finals, the problems have been set and tested by kingofnumbers (Hassan Jaddouh), me (kevinsogo), CherryTree (Sergey Kulik), utkarshl (Utkarsh Lath) and Antoniuk (Vasya Antoniuk), the translations were written by huzecong (Hu Zecong) for Mandarin, Antoniuk (Vasya Antoniuk) along with CherryTree (Sergey Kulik) for Russian and VNOI Team for Vietnamese. The contest admin and language verifier is PraveenDhinwa (Praveen Dhinwa).

Registrations:

• You can register in a team of two or can go solo into the contest. The Onsite Finale Mirror Contest starts at 12:00 PM 9 th July.

• If you are yet to register, you can do so here: https://www.codechef.com/teams/register/SNFL16MR.

• The contest format requires you to participate in a team of 2 or you can go solo. The prizes for the winners of the contest will be 5000 INR for the one who secures the first position and 3000 INR for the runner up.

See you all at the contest.

Regards,

Kevin Charles Atienza

Hello CodeForces Community!

Congratulations to all those who have cleared the SnackDown 2016 Qualifiers. We hope you are prepared for the Pre-Elimination Rounds. There will be two pre-elimination rounds and 1000+ teams ( to be precise, the top 1000 teams and teams with number of problems solved equal to 1000th team ) will be selected from each of the 2 rounds, Pre-Elimination Round A and Pre-Elimination Round B, who will further advance to the SnackDown 2016 Elimination.

The CodeChef SnackDown 2016 Pre-Elimination Round A begins tomorrow, at 9 PM IST, 4th June.

The problems have been set and tested by CherryTree (Sergey Kulik), Antoniuk (Vasya Antoniuk), and me (kevinsogo, Kevin Charles Atienza). The translations are written by huzecong (Hu Zecong), Antoniuk (Vasya Antoniuk), VNOI Team, CherryTree (Sergey Kulik), with PraveenDhinwa (Praveen Dhinwa) as contest admin. I hope you will enjoy solving the problems. Please feel free to give your feedback about the problems in comments below.

• Furthermore, this year, CodeChef will be inviting 52 teams (top 25 global + top 25 Indian + all Girl team + Indian school team) for the onsite finals. Of these 52 teams, 32 teams (top 15 each Global & Indian + Girl + Indian school team) will get an all-expense-paid trip to India, while the remaining 20 teams will be provided with accommodation and local travel in India. However, if any of these 20 teams win the competition, their travel fare will be reimbursed as well. It’s a win-win situation.

Along with the cash prizes for Global Winners, there are special prizes for Best School Team, Best Girls team and Best Indian Team (the total cash prizes are worth $22,500).

• The winning team shall win a whopping cash prize of $10,000.
• Also, taking into consideration the previous discussions regarding the timing of online elimination round of the contest, the organizers have decided to reschedule the round.

The new timings for the SnackDown 2016 Elimination Round are:

• Time: 19th June 2016, 7:30 pm to 12:30 am 20th June 2016 IST.

In order to accommodate the new timings, they have also rescheduled the June Cook-Off 2016. And the new timings for the June Cook-Off are:

Date & Time: 26th June 2016, 21:30 Hrs IST to 00:00 Hrs IST

I hope you like the new timings and that will enjoy the contest till the very end. That will be all from my side for now. See you all at the contest.

Regards,

Kevin

Hi all. I want to invite you to HourRank 9. The contest will take place tomorrow (exact time) on HackerRank. There are three problems to be solved in one hour.

For this round I wrote the problems. I hope you find them interesting! wanbo tested them, and other contributors (pre-solving, suggestions, technical help, etc.) are malcolm, satyaki3794, and Shafaet. Thank you for all your help!

The top 10 will get awesome HackerRank t-shirts. Editorials will be available at the end. Good luck and have fun!

Update: Score distribution : 30-50-80

Hi Coders!

Ad Infinitum is back with its 15th Edition, a contest restricted to the mathematics domain, held on HackerRank.

Register at https://www.hackerrank.com/infinitum15
The contest commences on 15^th April 15:30 UTC. You are allowed to enter the contest anytime. For tie breaking, the timer will start when you view the first challenge, which allows you to start late at your own convenience, but once started try to finish as fast as possible to be on top of the leaderboard :)

It's a 2-day contest with 8 problems (3 Easy(Tutorial), 3 Medium, 2 Hard)
Scoring Distribution: 20 25 30 40 60 80 90 100

Top 10 on leaderboard gets Cool HackerRank T shirts,

Detailed editorials will be available by the end of contest :) I suggest you try all challenges, and at the end of contest understand the solutions.

GL&HF