oj.uz

Submission #699192

# Submission time Handle Problem Language Result Execution time Memory
699192 2023-02-16T04:32:49 Z beepbeepsheep Naboj (COCI22_naboj) C++17
0 / 110
 268 ms 44176 KB 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

typedef tree<long long, null_type, less_equal<>,
        rb_tree_tag, tree_order_statistics_node_update>
        ordered_set;
#define ll long long
#define ii pair<ll,ll>
#define endl '\n'

const ll inf=1e15;
const ll maxn=2e5+5;
const ll mod=1e9+7;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

ll cnt[maxn][2];
bool vis[maxn];
set<ii> adj[maxn];
queue<ii> q;
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	ll n,m,a,b;
	cin>>n>>m;
	for (int i=0;i<m;i++){
		cin>>a>>b;
		adj[a].emplace(b,0);
		adj[b].emplace(a,1);
		cnt[a][0]++;
		cnt[b][1]++;
	}
	for (int i=1;i<=n;i++){
		if (cnt[i][0]==0){
			q.emplace(i,0);
		} else if (cnt[i][1]==0){
			q.emplace(i,1);
		}
	}
	stack<ii> s;
	while (q.size()){
		tie(a,b)=q.front();
		q.pop();
		for (auto [x,y]:adj[a]){
			adj[x].erase(make_pair(a,b));
			if (cnt[x][b]==1 && vis[x]==0){
				q.emplace(x,y);
				vis[x]=1;
			}
			cnt[x][b]--;
		}
		s.emplace(a,b);
	}
	for (int i=1;i<=n;i++){
		if (cnt[i][0] && cnt[i][1]){
			cout<<-1;
			return 0;
		}
	}
	cout<<s.size()<<endl;
	while (s.size()){
		cout<<s.top().first<<' '<<s.top().second<<endl;
		s.pop();
	}
	return 0;
}

Subtask #1
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9684 KB Output is correct
2 Correct 5 ms 9684 KB Output is correct
3 Correct 5 ms 9684 KB Output is correct
4 Correct 5 ms 9728 KB Output is correct
5 Correct 6 ms 9724 KB Output is correct
6 Correct 5 ms 9724 KB Output is correct
7 Correct 5 ms 9684 KB Output is correct
8 Incorrect 5 ms 9684 KB Output isn't correct
9 Halted 0 ms 0 KB -

Subtask #2
0 / 25.0

# Verdict Execution time Memory Grader output
1 Incorrect 268 ms 44176 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #3
0 / 70.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9684 KB Output is correct
2 Correct 5 ms 9684 KB Output is correct
3 Correct 5 ms 9684 KB Output is correct
4 Correct 5 ms 9728 KB Output is correct
5 Correct 6 ms 9724 KB Output is correct
6 Correct 5 ms 9724 KB Output is correct
7 Correct 5 ms 9684 KB Output is correct
8 Incorrect 5 ms 9684 KB Output isn't correct
9 Halted 0 ms 0 KB -