Путь в графе

/// https://informatics.msk.ru/mod/statements/view3.php?chapterid=160#1
#include <bits/stdc++.h>

using namespace std;

int main(){
    int n;
    cin >> n;
    int graph[n+1][n+1];
    vector < int > g[n+1];
    for (int i=1; i<=n; i++){
        for (int j=1; j<=n; j++){
            cin >> graph[i][j];
            if (graph[i][j] == 1){
                g[i].push_back(j);
                //g[j].push_back(i);
            }
        }
    }
    int s, f;
    cin >> s >> f;
    int used[n+1], dist[n+1], from[n+1]; // used[i] = 1, якщо <i> Була відвідана
    for (int i=0; i<=n; i++) used[i] = 0, from[i] = 0;
    vector < int > q;
    q.push_back(s);
    used[s] = 1;
    dist[s] = 0;
    int point = 0;
    while(point < q.size()){
        int v = q[point];
        for (int i=0; i<g[v].size(); i++){
            int to = g[v][i];
            if (used[to] == 0){
                used[to] = 1;
                from[to] = v;
                dist[to] = dist[v] + 1;
                q.push_back(to);
            }
        }
        point ++;
    }
    if (used[f] == 1){
        cout << dist[f] << endl;
        if (dist[f] > 0){
            vector < int > ans;
            while(f != 0){
                ans.push_back(f);
                //cout << f << ' ';
                f = from[f];
            }
            for (int i=ans.size()-1; i>-1; i--) cout << ans[i] << ' ';
        }
    }else cout << -1;
    return 0;
}
/*
Breadth First Search
*/