Breadth - First - Search

#include <bits/stdc++.h>
using namespace std;
queue<int>q;
int adj[101][101],d[101],p[101],n,c[101],a,b;
void bfs(int s) {
    for (int i=1;i<=n;i++) {
        d[i]=1000000000;
    }
    d[s] = 0;
    q.push(s);
    c[s]=1;
    while (!q.empty()) {
       int u = q.front();
       q.pop();
       for (int i=1;i<=n;i++) {
        if (adj[u][i]==1 && c[i]==0) {
            d[i] = d[u] + 1;
            c[i]=1;
            q.push(i);
            p[i]=u;
           }
       }
       c[u]==2;
    }
}
int main() {
    cin>>n>>a>>b;
    int ones=0;
    for (int i=1;i<=n;i++)
    for (int j=1;j<=n;j++)
    cin>>adj[i][j];
bfs(a);
if (d[b]==1000000000)
cout<<0<<endl;
else
cout<<d[b]<<endl;

    return 0;
}