oj.uz

답안 #905898

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
905898 2024-01-13T06:54:51 Z dsyz Network (BOI15_net) C++17
0 / 100
 4 ms 12376 KB 
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define MAXN (500005)
ll N, connectto1 = -1;
vector<ll> v[MAXN];
bool leaf[MAXN];
void dfs(ll x,ll p){
	ll children = 0;
	ll leafchildren = 0;
	for(auto u : v[x]){
		if(u != p){
			dfs(u,x);
			leafchildren += leaf[u];
			if(leafchildren >= 2) connectto1 = u;
			children++;
		}
	}
	if(children == 0){
		leaf[x] = 1;
	}
}
int main() {
	ios_base::sync_with_stdio(false);cin.tie(0);
	cin>>N;
	for(ll i = 0;i < N - 1;i++){
		ll a,b;
		cin>>a>>b;
		a--, b--;
		v[a].push_back(b);
		v[b].push_back(a);
	}
	dfs(0,-1);
	vector<ll> ans;
	for(ll i = 0;i < N;i++){
		if(leaf[i] && i != connectto1){
			ans.push_back(i + 1);
		}
	}
	cout<<ans.size() - 1<<'\n';
	cout<<1<<" "<<connectto1<<'\n';
	for(ll i = 1;i < ans.size();i++){
		cout<<ans[i - 1]<<" "<<ans[i]<<'\n';
	}
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:42:17: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |  for(ll i = 1;i < ans.size();i++){
      |               ~~^~~~~~~~~~~~

Subtask #1
0 / 18.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 4 ms 12376 KB Invalid number of links.
2 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 4 ms 12376 KB Invalid number of links.
2 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 4 ms 12376 KB Invalid number of links.
2 Halted 0 ms 0 KB -