Submission #705022

#	Time	Username	Problem	Language	Result	Execution time	Memory
705022		Paul_Liao_1457	Naboj (COCI22_naboj)	C++17	25 / 110	305 ms	524288 KiB

naboj

//記得跳題
//#pragma GCC optimize("O4,unroll_loops")
//#pragma GCC target("avx2")
#include<iostream>
#include<array>
#include<vector>
#include<string>
#include<algorithm>
#include<set>
#include<queue>
#include<stack>
#include<math.h>
#include<map>
#include<unordered_map>
#include<unordered_set>
#include<cstring>
#include<iomanip>
#include<bitset>
#include<tuple>
#include<random>
 
#define ll long long
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define pb push_back
#define INF (ll)(2e18)
#define F first
#define S second
#define endl "\n"
#define AC ios::sync_with_stdio(0);
 
using namespace std;
 
vector<pair<int, int> > e[200005];
vector<pair<int, int> > ans;

int last[200005], t, what[200005];
bool vis[200005];
bool ok=1;
 
void dfs(int now, int f, int up){
  if (up != -1) {
    ans.pb({now, up});
    what[now] = up;
    last[now] = ++t;
  }
  for (auto i:e[now]) if(i.F!=f){
    if(vis[i.F]) {
      ok = 0; return;
    }
    dfs(i.F,now,i.S);
    if(!ok) return;
  }
}

vector<pair<int, int> > edge;
 
signed main(){
  AC;
  int n, m; cin >> n >> m;
  FOR (i, 0, m) {
    int a, b; cin >> a >> b;
    edge.pb({a, b});
    e[a].pb({b, 0});
    e[b].pb({a, 1});
  }
  dfs(1,0,-1);
  
  if(!ok) {
    cout << -1 << endl; return 0;
  }

  cout << ans.size() << endl;
  for (auto i:ans) {
    cout << i.F << " " << i.S << endl;
  }
}

• Subtask 1: 0 / 15
• Subtask 2: 25 / 25
• Subtask 3: 0 / 70