제출 #538694

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
538694		S2speed	구슬과 끈 (APIO14_beads)	C++17	0 / 100	3 ms	2644 KiB

beads

#include<bits/stdc++.h>

using namespace std;

#define all(x) x.begin() , x.end()
typedef long long ll;
typedef pair<ll , ll> pll;

const ll maxn = 1e5 + 16 , inf = 2e16;

ll dp[maxn][2] , w[maxn];
vector<pll> adj[maxn];

void DFS(ll r , ll par){
	ll res = 0 , mx1 = -inf , mx2 = -inf;
	for(auto p : adj[r]){
		ll i = p.first , w = p.second;
		if(i == par) continue;
		DFS(i , r);
		ll h = max(dp[i][0] , dp[i][1] + w) , o = dp[i][0] + w - h;
		res += h;
		if(o > mx2){
			mx2 = o;
		}
		if(o > mx1){
			swap(mx1 , mx2);
		}
	}
	dp[r][1] = res + mx1;
	dp[r][0] = max(res , res + mx1 + mx2);
	return;
}

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

	ll n;
	cin>>n;
	for(ll i = 1 ; i < n ; i++){
		ll v , u , w;
		cin>>v>>u>>w; v--; u--;
		adj[v].push_back({u , w}); adj[u].push_back({v , w});
	}
	DFS(0 , -1);
	cout<<dp[0][0]<<'\n';
	return 0;
}

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