Submission #1264655

#	Time	Username	Problem	Language	Result	Execution time	Memory
1264655		mingga	Network (BOI15_net)	C++20	0 / 100	0 ms	328 KiB

net

// Author: caption_mingle
#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define ll long long
const int mod = 1e9 + 7;
const int inf = 2e9;
const int N = 5e5 + 7;
int n, deg[N];

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	#define task ""
	if(fopen(task ".INP", "r")) {
		freopen(task ".INP", "r", stdin);
		freopen(task ".OUT", "w", stdout);
	}
	cin >> n;
	for(int i = 1; i < n; i++) {
		int u, v; cin >> u >> v;
		deg[u]++;
		deg[v]++;
	}
	vector<int> vec;
	for(int i = 1; i <= n; i++) {
		if(deg[i] == 1) vec.pb(i);
	}
	cout << (sz(vec) + 1) / 2 << ln;
	for(int i = 0; i < sz(vec); i+= 2) {
		if(i == sz(vec) - 1) cout << vec[i] << ' ' << vec[0] << ln;
		else cout << vec[i] << ' ' << vec[i + 1] << ln;
	}
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:22:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |                 freopen(task ".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:23:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |                 freopen(task ".OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37