floyd warshall

#include <iostream>
#include <fstream>
using namespace std;

int n, cost[101][101];

void citire()
{
    ifstream f("grafFW.in");
    int i, j;
    f>>n;
    for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
            f>>cost[i][j];
}

int main()
{
    citire();
    int i, j, k;
    for(k=1;k<=n;k++)
        for(i=1;i<=n;i++)
            for(j=1;j<=n;j++)
                if(i!=j && i!=k && k!=j && cost[i][k]!=-1 && cost[k][j]!=-1 && (cost[i][j]>cost[i][k]+cost[k][j] || cost[i][k]==-1))
                    cost[i][j]=cost[i][k]+cost[k][j];

    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
            cout<<cost[i][j]<<" ";
        cout<<endl;
    }

}
/*
5
-1 -1 -1 -1 10
-1 -1 -1 10 -1
-1 -1 -1 -1 10
10 10 -1 -1 10
50 -1 10 10 -1
*/