### qwertsboy1234's blog

By qwertsboy1234, history, 5 weeks ago,

Here is a codechef problem Friends. Here is my solution ,its giving wrong answer.Can anybody help me find out the error.

#include<bits/stdc++.h>
using namespace std;
#define dd double
#define ll long long int
#define pb push_back
#define mp make_pair
#define fi first
#define sc second
#define pr pair<ll,ll>
#define pri pair<pr,ll>
#define pir pair<ll,pr>
#define ppr pair<pr,pr>
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
ll INF=1e18;
ll mod=1e9+7;
int main()
{
#ifndef ONLINE_JUDGE
freopen("inp.txt","r",stdin);
freopen("otpt.txt","w",stdout);
#endif
fastio;
ll te=1;
while(te--)
{
ll n,i,j,t;
cin>>n;
vector<vector<char> > v1(n,vector<char>(n));
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
cin>>v1[i][j];
}
}
ll ans=0;
queue<pr> q;
for(i=0;i<n;i++)
{
for(j=i+1;j<n;j++)
{
if(v1[i][j]=='0')
{
q.push(mp(i,j));
}
}
}
q.push(mp(-1ll,-1ll));
ll last=q.size();
ll ct=0;
while(1)
{
ct++;
pr p=q.front();
q.pop();
if(p.fi==-1)
{
if(last==q.size()||q.empty())
{
break;
}
last=q.size();
q.push(p);
continue;
}
ll i=p.fi,j=p.sc;
for(t=0;t<n;t++)
{
if(v1[t][i]=='1'&&v1[t][j]=='1'&&t!=i&&t!=j)
{
break;
}
}
if(t==n)
{
q.push(p);
continue;
}
if(v1[i][j]!='1')
{
ans+=1;
}
v1[j][i]='1';
v1[i][j]='1';
}
cout<<2*ans<<endl;
}
}