CODEWITHSUNDEEP
c++algorithmmemory
khaled baccour
khaled baccour

Reputation: 67

Can't seem to find the error - memory access violation

I'm trying to solve a problem on france IOI about a card game (named "Reussite" on level 4) that requires outputting every odd number, however I keep getting (0xC0000005) code if my input is bigger than about 48000 and I can't seem to find the error. Help!

here's my code:

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

int main() {
    ios::sync_with_stdio(false);
    int n;cin>>n;vector<int> arr(n+1);

    for (int i = 2; i < n+1; ++i) {
        int m = i;
        //error is in this while loop
        while (i*m<=n){arr[i*m]=1;m++;}
    }
    
   
    for (int i = 0; i < n+1; ++i) {
        if (arr[i]==0) printf("%d \n",i);
    }
}

Upvotes: 0

Views: 42

Answers (1)

Gassa
Gassa

Reputation: 8846

When the value n is at least 46341, its square no longer fits into a 32-bit signed integer, so the expression i*m results in an integer overflow.

You might want to cast the values to long long, like while ((long long)i*m<=n) or while (i*1LL*m<=n), or change your code otherwise.

Upvotes: 3

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