Обход графа

/// https://informatics.msk.ru/mod/statements/view3.php?chapterid=164#1
#include <bits/stdc++.h>

using namespace std;

int main(){
    int n, s;
    cin >> n >> s;
    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 used[n+1]; // used[i] = 1, якщо <i> Була відвідана
    for (int i=0; i<=n; i++) used[i] = 0;
    vector < int > q;
    q.push_back(s);
    used[s] = 1;
    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;
                q.push_back(to);
            }
        }
        point ++;
    }
    cout << q.size();
    return 0;
}