Submission #58946727

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Source Code Expand

/// Msaa el 5ra
#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define F first
#define S second
#define f(i, a, b) for (int i = a; i < b; i++)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define sz(x) (int)(x).size()
#define mp(x, y) make_pair(x, y)
#define popCnt(x) (__builtin_popcountll(x))
//#define int ll

using ll = long long;
using ii = pair<int, int>;
using ull = unsigned long long;

const int N = 2e5 + 5, A = 26, LG = 19, MOD = (119 << 23) +1, MOD2 = 1e9 + 7;
const long double PI = acos(-1);
const long double EPS = 1e-7;

const ll MAX = 1e15;

vector<int> adj[N];

void doWork() {
    int n, m;
    cin >> n >> m;
    while(m--) {
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
    }
    vector<int> dist(n + 1, -1);
    queue<int> q;
    q.push(1);

    while(q.size()) {

        auto cur = q.front();
        q.pop();
        if(cur == 1 && dist[cur] != -1) {
            cout << dist[cur] + 1 << "\n";
            return;
        }

        for(auto v : adj[cur]) {
            if(dist[v] == -1) {
                dist[v] = dist[cur] + 1;
                q.push(v);
            }
        }

    }

    cout << "-1\n";

}

int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int t = 1;
//  cin >> t;
  while (t--) {
    doWork();
  }
}

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