shank_punk's blog

Weird Runtime error!
By shank_punk, history, 9 years ago, In English

Hi guys. I tried implementing sieve today (I have done it 50+ times before), and my code was giving Runtime error :(

I tried to find out the error in my code but I don't know what is wrong. 


#include<bits/stdc++.h>
using namespace std;
bool vis[1000002];

int main(){
int i,j;
for(i=2;i<=100000;i++) vis[i]=true;

for(i=2;i<=100000;i++){

    if(!vis[i]) continue;

    for(j=i*i;j<=100000;j+=i){
        vis[j]=false;
    }
    //cerr<<i<<" ";
}

return 0;
}

If I change j+=i to j++, it does not show runtime error!(& the code will obviously be wrong & TLE)

UPDATE : Found my mistake(updated in comment section).

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9 years ago, # |
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UPDATE : I found out the error.

Its j = i*i. Since I declared i,j as int, 100000*100000 will cause overflow(don't know the exact technical term to be used). So I changed int to long long & it worked :)

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