Submission #1462550

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#define REP(i, a, n) for(ll i = ((ll) a); i < ((ll) n); i++)
using namespace std;
typedef long long ll;

ll N, M;
vector<ll> E[200000];

int main(void) {
  cin >> N >> M;
  REP(i, 0, M) {
    ll A, B;
    cin >> A >> B;
    A--;
    B--;
    E[A].push_back(B);
    E[B].push_back(A);
  }

  bool ans = false;
  REP(i, 0, E[0].size()) {
    REP(j, 0, E[E[0][i]].size()) if(E[E[0][i]][j] == N - 1) ans = true;
  }
  cout << (ans ? "POSSIBLE" : "IMPOSSIBLE") << endl;
}

Submission Info

Judge Result