제출 #977654

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
977654		TranGiaHuy1508	구슬과 끈 (APIO14_beads)	C++17	0 / 100	1 ms	500 KiB

beads

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

void main_program();

signed main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	main_program();
}

#define int long long

using ll = long long;
using ii = pair<int, int>;

const ll inf = 1e18;

int n;
vector<vector<ii>> adj;

vector<vector<ll>> dp;

void dfs(int x, int p = -1, ll pw = -inf){
	ll best1 = -inf, best2 = -inf;
	ll sum = 0;
	for (auto [k, w]: adj[x]){
		if (k == p) continue;

		dfs(k, x, w);

		sum += dp[k][0];
		ll delta = dp[k][1] - dp[k][0];

		if (delta > best1){
			best2 = best1;
			best1 = delta;
		}
		else if (delta > best2){
			best2 = delta;
		}
	}

	sum = max(sum, 0LL);

	dp[x][0] = max({sum, sum + best1 + best2, sum + best1 + pw});
	dp[x][1] = max({sum + pw, sum + best1 + best2 + pw});
}

void main_program(){
	cin >> n;

	adj.resize(n);
	
	for (int i = 0; i < n-1; i++){
		int x, y, w; cin >> x >> y >> w;
		x--; y--;
		adj[x].emplace_back(y, w);
		adj[y].emplace_back(x, w);
	}

	dp.assign(n, {0, 0});
	dfs(0);

	cout << dp[0][0] << "\n";
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43