제출 #844804

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
844804		irmuun	Duathlon (APIO18_duathlon)	C++17	0 / 100	43 ms	14172 KiB

count_triplets

#include<bits/stdc++.h>
 
using namespace std;
 
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    ll n,m;
    cin>>n>>m;
    vector<ll>adj[n+1];
    for(ll i=1;i<=m;i++){
        ll u,v;
        cin>>u>>v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    if(m==n-1){
        ll ans=0;
        vector<ll>cnt(n+1,0);
        function <void(ll,ll)> dfs=[&](ll x,ll p){
            cnt[x]=1;
            vector<ll>v;
            for(ll y:adj[x]){
                if(y!=p){
                    dfs(y,x);
                    v.pb(cnt[y]);
                    cnt[x]+=cnt[y];
                }
            }
            v.pb(n-cnt[x]);
            for(ll y:v){
                ans+=(n-1-y)*y;
            }
        };
        dfs(1,-1);
        cout<<ans;
    }
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10