Submission #764764

#	Time	Username	Problem	Language	Result	Execution time	Memory
764764		vjudge1	Network (BOI15_net)	C++17	0 / 100	1 ms	296 KiB

net

#include <bits/stdc++.h>
#define file(s) if (fopen(s".in", "r")) freopen(s".in", "r", stdin), freopen(s".out", "w", stdout)
#define Youarestupid ios_base::sync_with_stdio(NULL);cin.tie(0);cout.tie(0);
#define all(x) x.begin() , x.end()
#define int long long
#define pb push_back
#define ins insert
#define sz size()
#define F first
#define S second
const int N = 1e5 + 70 , inf = 1e18 + 77 , MOD = 1e9 + 7;
const double eps = 1e-11;
using namespace std;
int T = 1 , sum , a[N] , t[N * 4] , q[N * 4];
int binpow(int a , int b){
    if (!b) return 1;
    if (b % 2){
        return (a * binpow(a , b - 1)) % MOD;
    }
    else{
        int val = binpow(a , b / 2);
        return (val * val) % MOD;
    }
}

void solve(){
	int n;
	cin >> n;
	vector < int > g[n + 5];
	for(int i = 1; i < n; i++){
	    int x , y;
	    cin >> x >> y;
	    g[x].pb(y);
	    g[y].pb(x);
	}
    vector < int > v;
    bool ok = 1;
    int x = 0;
    for(int i = 1; i <= n; i++){
        if(g[i].sz == 1){
            v.pb(i);
            if(ok){
                x = i;
            }
            ok = 0;
        }
    }
    if(v.sz == 1){
        cout << 1 << '\n';
        cout << x << ' ' << (x + 1) % x;
        return;
    }
    if(v.sz % 2 == 1){
        v.pb(x);
    }
    cout << (v.sz) / 2 << '\n';
    for(int i = 0; i < v.sz - 1; i += 2){
        cout << v[i] << ' ' << v[i + 1] << '\n';
    }
    // if(v.sz % 2 == 1){
    //     cout << v[v.sz - 1] << ' ' << (v[v.sz - 1] + 1) % v[v.sz - 1];
    // }
}

signed main(){
// 	cin >> T;
    while(T--){
    	solve();
    }
}
/*

*/

Compilation message (stderr)

net.cpp: In function 'void solve()':
net.cpp:57:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |     for(int i = 0; i < v.sz - 1; i += 2){
      |                    ~~^~~~~~~~~~

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