제출 #1095687

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1095687		shidou26	Network (BOI15_net)	C++14	100 / 100	273 ms	65616 KiB

net

#include <bits/stdc++.h>
using namespace std;

#define endl '\n'
#define all(v) v.begin(), v.end()
#define filter(v) v.resize(unique(all(v)) - v.begin())

typedef long long ll;
typedef pair<int, int> ii;

const int MOD = 1e9 + 7;
inline ll add(ll x, ll y, ll mod = MOD) {return ((x % mod) + (y % mod)) % mod;}
inline ll sub(ll x, ll y, ll mod = MOD) {return ((x - y) % mod + mod) % mod;}
inline ll prod(ll x, ll y, ll mod = MOD) {return ((x % mod) * (y % mod)) % mod;}

const int N = 1e6 + 3;

int n;
int eu[N], ev[N];
vector<int> adj[N];

int timer = 0;
int pos[N], leaves[N];

void prepare() {

}

void input() {
	cin >> n;

	for(int i = 1; i < n; i++) {
		int u, v; cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
}

void dfs(int u, int prev) {
	for(int i = 0; i < (int)adj[u].size(); i++) {
		int v = adj[u][i];
		if(v != prev) {
			dfs(v, u);
		}
	}

	if(adj[u].size() == 1) {
		pos[u] = ++timer;
		leaves[timer] = u;
	}
}

void process() {
	int leaf = 0;
	for(int i = 1; i <= n; i++) leaf += (adj[i].size() == 1);
	cout << (leaf + 1) / 2 << endl;

	dfs(1, -1);
 	if(timer & 1) leaves[++timer] = leaves[1];
	for(int i = 1; i + timer / 2 <= timer; i++) {
		cout << leaves[i] << " " << leaves[i + timer / 2] << endl;
	}
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    #define task "Date_A_Live"
    if(fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }

    prepare();

    int tc = 1; // cin >> tc;

    for(int i = 1; i <= tc; i++) {
        input();
        process();
    }

    cerr << "Saa, watashtachi no deito hajimemashou" << endl;

    return 0;
}

/*
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*/

컴파일 시 표준 에러 (stderr) 메시지

net.cpp: In function 'int main()':
net.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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