Codeforces round 883 Editorial

#	User	Rating
1	tourist	3985
2	jiangly	3814
3	jqdai0815	3682
4	Benq	3529
5	orzdevinwang	3526
6	ksun48	3517
7	Radewoosh	3410
8	hos.lyric	3399
9	ecnerwala	3392
9	Um_nik	3392

#	User	Contrib.
1	cry	169
2	maomao90	162
2	Um_nik	162
4	atcoder_official	161
5	djm03178	158
6	-is-this-fft-	157
7	adamant	155
8	awoo	154
8	Dominater069	154
10	luogu_official	150

Hint 1

Hint 2

Tutorial

Solution

#include <iostream>

using namespace std;


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

	for (int test_case = 0; test_case < test_cases; test_case++) {
		int n;
		cin >> n;
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int a, b;
			cin >> a >> b;
			if (a > b)
				ans++;
		}
		cout << ans << endl;
	}

	return 0;
}

Rate the problem

1846B - Rudolph and Tic-Tac-Toe

Author: Sasha0738

Hint 1

Tutorial

Solution

#include <iostream>
#include <vector>
#include <string>


using namespace std;

int main() {
	int test_cases;
	cin >> test_cases;
	for (int test_case = 0; test_case < test_cases; test_case++) {
		vector<string> v(3);
		for (int i = 0; i < 3; i++)
			cin >> v[i];
		string ans = "DRAW";
		for(int i = 0; i < 3; i++) {
			if (v[i][0] == v[i][1] && v[i][1] == v[i][2] && v[i][0] != '.')
				ans=v[i][0];
		}
		for (int i = 0; i < 3; i++) {
			if (v[0][i] == v[1][i] && v[1][i] == v[2][i] && v[0][i] != '.')
				ans=v[0][i];
		}
		if (v[0][0] == v[1][1] && v[1][1] == v[2][2] && v[0][0] != '.')
			ans=v[0][0];
		if (v[0][2] == v[1][1] && v[1][1] == v[2][0] && v[0][2] != '.')
			ans=v[0][2];
		cout << ans << endl;
	}
	return 0;
}

Rate the problem

1846C - Rudolf and the Another Competition

Author: vladmart

Hint 1

Hint 2

Tutorial

Solution

#include <bits/stdc++.h>

#define int long long

using namespace std;

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int ttt;
    cin >> ttt;
    while(ttt--){
        int n, m, h;
        cin >> n >> m >> h;
        pair<int, long long> rud;
        int ans = 1;
        for(int i = 0; i < n; i++){
            vector<int> cur(m);
            for(int j = 0; j < m; j++){
                cin >> cur[j];
            }
            std::sort(cur.begin(), cur.end());
            int task_cnt = 0;
            long long penalty = 0, sum = 0;
            for(int j = 0; j < m; j++){
                if (sum + cur[j] > h) break;
                sum += cur[j];
                penalty += sum;
                task_cnt++;
            }
            if (i){
                if (make_pair(-task_cnt, penalty) < rud) ans++;
            } else rud = {-task_cnt, penalty};
        }
        cout << ans << '\n';
    }
    return 0;
}

Rate the problem

1846D - Rudolph and Christmas Tree

Author: vladmart

Hint 1

Hint 2

Hint 3

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    cout.precision(10); cout.setf(ios::fixed);
    int ttt;
    cin >> ttt;
    while (ttt--) {
        int n, d, h;
        cin >> n >> d >> h;
        vector<int> y(n);
        for(int i = 0; i < n; i++){
            cin >> y[i];
        }
        long double ans = (long double)d * h / 2.0;
        for (int i = 0; i + 1 < n; ++i) {
            if (y[i + 1] >= y[i] + h) ans += (long double)d * h / 2.0;
            else{
                long double d2 = (long double)d * (y[i] + h - y[i + 1]) / h;
                long double nh = y[i + 1] - y[i];
                ans += (d + d2) / 2.0 * nh;
            }
        }
        cout << ans << '\n';
    }
    return 0;
}

Rate the problem

1846E1 - Rudolf and Snowflakes (simple version)

Author: natalina

Hint 1

Hint 2

Hint 3

Tutorial

Solution

#include<bits/stdc++.h>

using namespace std;

using LL = long long;

set<long long> nums;

int main() {

    for (long long k = 2; k <= 1000; ++k) {
        long long val = 1 + k;
        long long p = k*k;
        for (int cnt = 2; cnt <= 20; ++cnt) {
            val += p;
            if (val > 1e6) break;
            nums.insert(val);            
            p *= k;
        }
    }



    int _ = 0, __ = 1;
    cin >> __;

    for (int _ = 0; _ < __; ++_) {
        long long n;
        cin >> n;
        

        if (nums.count(n)) cout << "YES" << endl;
        else cout << "NO" << endl;

    }


    return 0;
}

Rate the problem

1846E2 - Rudolf and Snowflakes (hard version)

Author: natalina

Hint 1

Hint 2

Hint 3

Hint 4

Tutorial

Solution

#include<bits/stdc++.h>

using namespace std;

using LL = long long;

set<long long> nums;

int main() {

    for (long long k = 2; k <= 1000000; ++k) {
        long long val = 1 + k;
        long long p = k*k;
        for (int cnt = 3; cnt <= 63; ++cnt) {
            val += p;
            if (val > 1e18) break;
            nums.insert(val);
            if (p > (long long)(1e18) / k) break;
            p *= k;
        }
    }



    int _ = 0, __ = 1;
    cin >> __;

    for (int _ = 0; _ < __; ++_) {
        long long n;
        cin >> n;
        if (n < 3)
        {
            cout << "NO" << endl;
            continue;
        }
        long long d = 4*n - 3;
        long long sq = sqrt(d);
        long long sqd = -1;
        for (long long i = max(0ll, sq - 5); i <= sq + 5; ++i) {
            if (i*i == d)
            {
                sqd = i;
                break;
            }
        }
        if (sqd != -1 && (sqd - 1) % 2 == 0 && (sqd - 1) / 2 > 1)
        {
            cout << "YES" << endl;
            continue;
        }

        if (nums.count(n)) cout << "YES" << endl;
        else cout << "NO" << endl;

    }


    return 0;
}

Rate the problem

1846F - Rudolph and Mimic

Author: Sasha0738

Hint 1

Hint 2

Tutorial

Solution

#include <iostream>
#include <vector>
#include <map>

using namespace std;

int main() {
	int test_cases;
	cin >> test_cases;
	for (int test_case = 0; test_case < test_cases; test_case++) {
		int n;
		cin >> n;
		vector<int> v(n);
		map<int, int> m;
		for (int i = 0; i < n; i++) {
			cin >> v[i];
			m[v[i]]++;
		}
		vector<int> elements_to_erase;
		int ans;
		for (int i = 0; i < 5; i++) {
			if (v.size() - elements_to_erase.size() == 1) {
				cout << "! " << ans << endl;
				break;
			}
			cout << "- " << elements_to_erase.size() << " ";
			for (int j = 0; j < elements_to_erase.size(); j++) {
				cout << elements_to_erase[j] << " ";
			}
			cout << endl;
			vector<int> new_v;
			map<int, int> new_m;
			for (int j = 0; j < v.size() - elements_to_erase.size(); j++) {
				int x;
				cin >> x;
				new_v.push_back(x);
				new_m[x]++;
			}
			elements_to_erase.clear();
			int tm = -1;
			for (auto& k : new_m) {
				if (k.second > m[k.first]) {
					tm = k.first;
				}
			}
			if (tm != -1) {
				for (int j = 0; j < new_v.size(); j++) {
					if (new_v[j] != tm)
						elements_to_erase.push_back(j + 1);
					else
						ans = j + 1;
				}
				m.clear();
				m[tm] = new_m[tm];
			}
			v = new_v;
		}
	}
	return 0;
}

Rate the problem

1846G - Rudolf and CodeVid-23

Author: vladmart

Hint 1

Hint 2

Hint 3

Tutorial

Solution

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int ttt;
    cin >> ttt;
    while (ttt--) {
        int n, m;
        cin >> n >> m;
        bitset<10> tmp;
        cin >> tmp;
        int s = (int) tmp.to_ulong();
        vector<pair<pair<int, int>, int>> edges(m);
        for (int i = 0; i < m; i++) {
            cin >> edges[i].second;
            cin >> tmp;
            edges[i].first.first = ((1 << n) - 1) ^ (int) tmp.to_ulong();
            cin >> tmp;
            edges[i].first.second = (int) tmp.to_ulong();
        }
        vector<int> dist(1 << n, INT_MAX);
        dist[s] = 0;
        set<pair<int, int>> q = {{0, s}};
        while (!q.empty()) {
            auto [d, v] = *q.begin();
            q.erase(q.begin());
            for (int i = 0; i < m; i++) {
                int to = v & edges[i].first.first;
                to |= edges[i].first.second;
                if (dist[to] > d + edges[i].second) {
                    q.erase({dist[to], to});
                    dist[to] = d + edges[i].second;
                    q.insert({dist[to], to});
                }
            }
        }
        if (dist[0] == INT_MAX) dist[0] = -1;
        cout << dist[0] << '\n';
    }
    return 0;
}

Rate the problem

#include <bits/stdc++.h> using namespace std; long long int sumpow(long long int x, int y) { long long int p=1; for(int i=1;i<=y;i++) { p=1+x*p; } return p; } int main() { int t; cin>>t; for(int i=1;i<=t;i++) { long long int n; cin>>n; int decider=0; for(long double j=2;j<(log(n)/log(2));j++) { long long int c=powl(n,1/j); if(sumpow(c,j)==n) { decider=1; cout<<"YES"<<endl; break; } } if(decider==0) { cout<<"NO"<<endl; } } return 0; }

for (int i = 0; i < m; ++i) { for (int mask = 0; mask < 1 << 10; ++mask) { // cost[mask] = cost for getting this much protection if ((damage[i] & mask) == damage[i]) { minSelf(cost[save[i] | mask], cost[mask] + days[i]); } } }

import sys input=sys.stdin.readline for _ in range(int(input())): n=int(input()) for i in range(2,61): a=int(n**(1/i)) if a==1: print("NO") break c=1 ae=0 t=0 while ae<n: ae+=c c=c*a t+=1 if ae==n and t>2: print("YES") break else: print("NO")

Comments (87)

Show archived | Write comment?

not_ahmed_hamed

18 months ago, # |

+13

HacksForces

→ Reply

Zhiyong99

17 months ago, # ^ |

Hahaha

naman.gokhru.mst20

10 months ago, # ^ |

Hahaha Hahaha

MONISM

← Rev. 3 →

For E2 there is a simpler solution to check if there exists a $$$k$$$ such that $$$1 + k + k ^2 = n$$$.

You can rearrange the equation to $$$k(k + 1) = n - 1$$$. It follows that the only $$$k$$$'s you need to check are $$$\lfloor \sqrt{n - 1}\rfloor$$$ and $$$\lfloor \sqrt{n - 1}\rfloor - 1$$$. This is a modified version of the official solution : code

EDIT : as davi-v pointed out,there is no need to check for $$$\lfloor \sqrt{n - 1}\rfloor - 1$$$.

xiojoy

18 months ago, # ^ |

Great!

sagar1213

can you explain why are checking the equation for k=2 and why we only floor(sqrt(n — 1)) and floor(sqrt(n — 1)) — 1 ?

Sure! I assume you meant $$$exponent = 2$$$,not $$$k = 2$$$. If you deal with all $$$k$$$ $$$<=$$$ $$$10 ^ {6}$$$ (for example by precalculating a set of valid numbers),for all other $$$k$$$ $$$>$$$ $$$10 ^ {6}$$$ the exponent must be exactly $$$2$$$. That is because the minimmum exponent is $$$2$$$ and if the exponent was $$$3$$$ the sum would be larger than $$$10 ^{18}$$$.Now we have to check that there exists a $$$k$$$ such that $$$1 + k + k ^2 = n$$$. This is the same as checking if there is a $$$k$$$ such that $$$k(k + 1) = n - 1$$$. Now, let $$$r = \sqrt{n - 1}$$$. It is easy to see that $$$k < r$$$. However, $$$k$$$ must be as large as possible so $$$k$$$ is either $$$\lfloor r \rfloor$$$ or $$$\lfloor r \rfloor - 1$$$ when $$$n - 1$$$ is a perfect square.

I want to say like for p=2 the equation would be 1+k+k^2. So why we have taken for p=2 if the no. Is not found in precalculated array.

natalina

Because for n <= 10¹⁸ and p = 2 the value of k could be approximately sqrt(n) = 10⁹. But we can precalc values only for k <= 10⁶

1+k+k^2=n how do we get to this ?

This is formula for the number of vertexes in minimal snowflake. 1 vertex at the initial value, k vertexes at the second layer and k^2 vertexes at the third one.

SerbanC

Very inefficient approach. It can be done with binary search sir !!!

Aqin7

can u explain "if (p > (long long)(1e18) / k) break;" Why this statement is necessary?

← Rev. 2 →

The if statement is necessary because otherwise the sum could overflow. If you have to check if $$$a \cdot b > val$$$ , a neat way of doing this and avoiding overflow is checking if $$$a > val / b$$$. Hope this helps!

Thank u for your reply, i got it:)

davi-v

You don't need to check $$$\lfloor{\sqrt{n-1}}\rfloor - 1$$$. Let $$$m = n - 1$$$. For $$$k(k+1)=k^2+k$$$ to be $$$m$$$, $$$k < \sqrt{m}$$$. Let $$$x = \lfloor\sqrt{m}\rfloor$$$. The question is: which numbers of the form $$$k=x-c$$$, $$$c \ge 0$$$ do we need to check?

Substituting in $$$k(k+1)$$$, we get $$$(x-c)(x-c+1)=x^2+x(-2c+1)+c^2-c$$$. Note that $$$x(-2c+1)+c^2-c$$$ must be $$$\ge 0$$$, as $$$x^2 \le m$$$. We need to show that if $$$c > 0$$$, $$$x(-2c+1)+c^2-c < 0$$$, so $$$x^2+x(-2c+1)+c^2-c$$$ can't equal $$$m$$$.

Note $$$c \le x$$$, otherwise $$$k$$$ would be negative. Let $$$x = c + d, d \ge 0$$$. Substituting, we get

$$$ x(-2c+1)+c^2-c = (c+d)(-2c+1)+c^2-c\\ =-2c^2+c-2cd+d+c^2-c=-c^2-2cd+d. $$$

If $$$c > 0$$$, $$$-c^2-2cd+d=-c^2+d(-2c+1) < 0$$$, as $$$-c^2 < 0$$$ and $$$-2c+1 \le 0$$$.

You are correct! Thank you for pointing out my mistake, I will make sure to correct it shortly. Also, I found a simpler proof to prove we don't need to check $$$ \lfloor \sqrt{n - 1}\rfloor$$$ :

I claim that for any number $$$a = k ^ {2},k\in\mathbb{N},\nexists b \in \mathbb{N}$$$ such that $$$b \cdot (b + 1) = a$$$. When $$$b = k,b \cdot(b + 1) > a$$$ and when $$$b <= k - 1,b \cdot(b + 1) < a$$$. Because $$$b \cdot(b + 1)$$$ is either $$$>$$$ or $$$<$$$ than $$$a$$$,we can conclude that $$$b \cdot(b + 1) \neq a$$$.

expertaq

E2 is a superb binary search question, liked it

leducphuclong

I did think about BS in the cts, but I couldn't go with that, can you tell me that solution ?

WarriorOfLiberation

If you still haven't got the idea a more simpler bs solution is consider 1+k+k^2+..k^p, observe that this is less than k^(p+1) and as well observe that the maximum value of p can be 63 since any power greater than p and the sum>1e18, so from here we can bruteforce for all powers and for this power we can upper bound the value of k by n^(1/p), and binary search which value of k satisfies 1+k+...k^p==n, if any confusion feel free to ask.

V1N17

Can you please explain the concept of n^(1/p). I am not getting this part.

So if it's something like if 1+k+k^2+..+k^p=n then k^(p+1)>n, you can easily deduce that I think(correlate it with binary recall that bit set at position i is bigger than all combined from i-1 to 1), so from k^(p+1)>n, we get got any k greater than n^(1/(p+1)) we definitely can't get the answer so that is the upper bound, hope it helps.

got it,thanks.

sanwal_aditya

Hi, can anyone help me debug my submission for E2? Don't know why I am getting WA.Thanks in advance.212818653

roycf123

I tried the similar approach in python (no overflow) and got WA on tc 16 after increasing the max value upto 1e25... (was AC initially and finally got hacked :(( )

Further increment gave TLE... maybe the constraints weren't designed for the binary search solution... (unless I'm wrong, in which case I would appreciate if someone pls provided me with an AC solution)

P.S: My initial approach in C++ was returning LLONG_MAX in the binpow function whenever overflow occured (used a check_overflow() function...) which gave WA on tc 5... Idk why...

i3mr125

why is the D in editorial AC without setprecision? what differs from my submission . ik i messed up the setprecision in my code but still why

Precision is set before the solution code at the beginning of the main function

wow didn't notice. nice info ty

neelesh510

-16

At the time of contest 1846C is accepted so I have done 4th but next day it is showing wrong on test case 10. it's your fault not mine.

Abito

it's your fault

It's plateform fault because it is showing correct how can I know it fails on some test case

After contests end more tests are added

gardengnome

From the announcement: "The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks."

This is part of typical D3 rounds: you will not know whether your solution passes all tests during the contests, and this challenges you to think carefully about special and corner cases and thus helps to improve your skills.

iamneerajhari

← Rev. 6 →

+23

For E2, there is a much simpler code arising from the result of an inequality.

We can just iterate through the values of p. For each p, we need to check for only a single value of k which is floor(n^(1/j)). This is the only possible value of k that may satisfy the condition for a given value of p. This is because:

k^p < 1+k+(k^2)+....+(k^p) < (1+k)^p implies k < (1+k+(k^2)+....+(k^p))^(1/p) < 1+k

If n is equal to 1+k+(k^2)+....+(k^p), then k should be less than n^(1/p) and as per the above inequality k should be floor(n^(1/p)).

Here's the code.

So we can take one medicine multiple times in G?

vgtcross

← Rev. 9 →

+20

It doesn't matter if it's allowed or not since it would never actually be useful to take the same medicine multiple times anyway.

I claim that if there is a sequecne of medicine that removes all symptoms and medicine $$$x$$$ is used multiple times, we can keep the last occurrence of $$$x$$$ and remove all earlier ones, and the sequence stays valid.

Proof: Consider the symptoms medicine $$$x$$$ cures. It doesn't matter if these symptoms are cured or not before the last occurrence of $$$x$$$ since the last time of taking medicine $$$x$$$ cures these symptoms anyway. Thus, taking medicine $$$x$$$ also earlier has no effect.

Now consider the symptoms medicine $$$x$$$ gives. It doesn't matter if these symptoms are cured or not before the last occurrence of $$$x$$$ since taking this medicine will give these symptoms anyways, and they need to be cured later. Thus, taking medicine $$$x$$$ also earlier has no effect.

This means that taking medicine $$$x$$$ also earlier than the last occurrence has no effect on any symptoms. $$$\square$$$

kevintooorz

this round has really weak testcases. It's not only for B and C, but also for G. This is my submission for G, in no way should it pass but still it passes.

Your solution is fine (why I don't know), check the announcement page someone explained why this works

tosivanmak

ummm... the solution takes at most 20 medicine.

Yes, but your solution is still correct. It can be shown that we never need more than 10 medicine to get fully cured, here is a short explanation (without proof). I can provide a proof if you can't see why that is true.

apex

My Solution Pretty sure , I have the same solution as that of the editorial . Dunno why I got the TLE though

Nxxlt

Use fast input. Passed in 202 ms. Code: 215151784

aradhyeagarwal

Any idea why this submission is giving a WA for D? I have just subtracted the overlapping area instead of using the trapezium formula.`

https://mirror.codeforces.com/contest/1846/submission/212715188

olegmak

setprecision() goes before output we set precicion for

dhruv1807

1846-C - Rudolf and the Another Competition

Any idea why my submission gets a TLE here. Time complexity is O(n*mlogm). 212937677

Spoiler

import sys

from os import path

input = sys.stdin.readline

if(path.exists('input.txt')): sys.stdin = open("input.txt","r") sys.stdout = open("output.txt","w")

def listInp(): return list(map(int,input().split()))

def mapInp(): return map(int,input().split())

for _ in range(int(input())):

n,m,h = mapInp()

data = []

for i in range(n):
    data.append(sorted(listInp()))

psums = []

for i in range(n):
    x = [0]
    for j in range(m):
        if data[i][j] + x[-1] <= h:
            x.append(data[i][j] + x[-1])
        else:
            break

    psums.append([len(x)-1,sum(x),i])

psums.sort(key=lambda x:(-x[0],x[1]))

# print(psums)

for i in range(n):
    if psums[i][2] == 0:
        print(i+1)
        break

hukevraainy

can python sqeeze through C and D without TLE?

here's my code and they seem to not work even tho the complexity is exactly identical to the editorial

https://mirror.codeforces.com/contest/1846/submission/212613024 (C)

https://mirror.codeforces.com/contest/1846/submission/212645926 (D)

an explanation or help would be wonderful.

1xx55

For D you can see my submission here 212968791 (I just change your code a little and get accepted)

bidvamaxim

My solution in B does not require a review of 4 cases.

MichaelR.Moussa

well , i am still a beginner, but in problem 3 ... i don't get how did we store the solution times for each student by this :

for(int i = 0; i < n; i++){ vector cur(m); for(int j = 0; j < m; j++){ cin >> cur[j]; }

while this should only store the last student only since it overwrites the existing values in each new outer loop ?

You're correct; this only stores the solution times for the last student. But notice that right after reading this, we already handle this student by calculating the optimal number of problems and minimum time penalty for this student. Thus, we don't need to store the problem-specific times for any longer and they can be overwtitten by new data.

pgiaminh8368

-8

212951522 For problem F, why does this code give Idleness Limit Exceeded

You output mimic position before reading full response from OJ

ankitghanghas1072

17 months ago, # |

In E2, can somebody tell me the value of k that satisfy 29th test case i.e. n = 64000160000400001, I think this test case is wrong.

+16

400,000

Krzychuo

Dial's algorithm can be used in G to achieve $$$O(2^n \cdot (m + MAXd))$$$ complexity. 212963777

I did think about BS at E2 in the cts, but I couldn't go with that, someone please tell me the editorial of that solution, I really need it. Thank you.

Assume that we have an array {$$$a_k$$$} satisfied $$$a_k = k^2+k+1$$$ , then we can see $$${a_k}$$$ is increasing when k increases. So BS works on this array. We can use BS to check whether the given $$$n$$$ is in {$$$a_k$$$}.Pick $$$l$$$=2 and $$$r$$$=minimum $$$k$$$ satisfied $$$a_k > 10^{18}$$$ and BS.Then we can check $$$b_k = k^3+k^2+k+1 $$$ , $$$c_k = k^4+k^3+k^2+k+1 $$$ ... till $$$A_k = k^{63}+k^{62}+...+k+1$$$ .If the given $$$n$$$ doesn't stay in the arrays mentioned above , the answer is "NO".

You don't really need to construct these arrays and store the value of them (MLE) , just calculate $$$a_{mid}$$$ and compare $$$a_{mid}$$$ with the given $$$n$$$ .

YoMamaLover

In problem G, you should have mentioned that you can use a medicine several times because without it the problem seems quite complicated. By the way, does anyone know if it's possible to solve the problem if we can use each medicine only once?

CandidateMasterHuMaiAab

this is my submission for this problem submission. When we use one medicine at a time then we just have to make the following change in the code

I just swapped the two loops of dp just like we do in coin change dp problem.

_MASTER__

check this

yuuma

Try to solve E2 with binary search, Don't know what I've missed

https://mirror.codeforces.com/contest/1846/submission/212862518

Line 11: i<62

It should be i<64 i think

abcsumits

← Rev. 4 →

this solution is accepted in e1 but not in e2,provide me some reason, let n=1+x+x^2......+x^i ------ eq(1) now, we know, x^i<n<(x+1)^i (by binomal theorm) that, means x<n^(1/i)<x+1, now x can be gif(n^(1/i)), we will satisfy eq(1) with x, if it is true ans exist. we will do it for i between 2 to 61.

Hey your solution is too slow, the bound for the largest power is incorrect as well, check for i<=63, since 2^63~1e18, it will still tle with the current solution though, check this for an alternate approach my approach

it would be 60, and now it's tle, but complexity for each case woould be logn*logn*60

By your approach right, mine is a simple binary search that's just logn*63

my solution is giving tle now :(

your apporach is logn*logn*60 too

How is this 212715312 logn*logn*60?

leave it i have used inbuilt pow function in python

Vinayak286

In E2 , for n greater 1e12 we can directly use Shree Dharacharya formula to know whether a k exist or not. And for k from 1 to 1e6 we can make a set of sum of G.P . I got this intuition in the contest but was getting TLE while calculating the sum of G.P . :( Got accepted in 1 try post contest.

Ahmed_Solyman

Why there is Rudolph and Rudolf?

cftryharder

Can somebody help me to spot why is giving Idleness Limit Exceeded?

https://mirror.codeforces.com/contest/1846/submission/213728138

I've tried several things, but still can't find the issue.

arpcode

Same bro, did you find the issue?

armurox

Hi, could anyone help debug my submission? This is for 1846B. My submission is https://mirror.codeforces.com/contest/1846/submission/214305302

Thanks in advance!

Arnur2937

Note that after finding a winner when you check rows and columns, you just break for loop, meaning you are checking diagonals even if you found the winner.

hhc0716

What a deceitful problem C!

what is k for 1000015000057 in 11th test in E2?

tr1ten

15 months ago, # ^ |

K=1000007 level=1

thanks

Why do I get a Idleness Limit Exceeded on my code for F? [Code] Please help

MickeyIsAwesome

Hello guys, in 1846F - Rudolph and Mimic, continously getting time limit exceeded, even though I have verified my solution with editorial, and have tried to match it to the author's solution. Can anyone please let me know what could be the issue here :( -> 216464518

alpha1215

11 months ago, # |

alternate dp solution for G

code

#include<bits/stdc++.h>
using namespace std; 
char nl = '\n';
using i64 = long long;

void solve(int t) {
    // cout << "test #" << t << << nl;
    int n, m; cin >> n >> m;
    string ds; cin >> ds;
    int dsn = 0;
    for(int b = 0; b < n; b++) {
        if(ds[b] == '1') dsn |= 1 << b;
    }
    vector<array<int, 3>> med(m);
    for(int i = 0; i < m; i++) {
        cin >> med[i][0];
        string cure, dis; cin >> cure >> dis;
        for(int b = 0; b < n; b++) {
            if(cure[b] == '1') med[i][1] |= 1 << b;
            if(dis[b] == '1') med[i][2] |= 1 << b;
        }
    }
    if(dsn == 0) {
        cout << 0 << nl; return;
    }
    vector<int> dp(1 << n, INT_MAX);
    for(int i = (1 << n) - 1; i >= 0; i--) {
        if((i | dsn) == i) dp[i] = 0;
    }
    for(int i = (1 << n) - 1; i >= 0; i--) {
        for(auto& a : med) {
            if((i | a[2]) == i && dp[i | a[1]] != INT_MAX) dp[i] = min(dp[i], dp[i | a[1]] + a[0]);
        }
    }
    cout << (dp[0] == INT_MAX ? -1 : dp[0]) << nl;
}   

int main() {
    int tt = 1;
    cin >> tt;
    for(int t = 1; t <= tt; t++) solve(t);
}

J_Jain

8 months ago, # |

1846G is really a nice question,lovely

pcumamahesh

6 months ago, # |

I really liked the author's solution to G. Taught me how to modify Dijkstra's algorithm for dense graphs like this.

practice_cpp

5 months ago, # |

Can anyone explain why i am getting WA on test 10 on E1 273463635

natalina's blog