Submission #552166

#	Time	Username	Problem	Language	Result	Execution time	Memory
552166		QwertyPi	Beads and wires (APIO14_beads)	C++14	0 / 100	3 ms	4948 KiB

beads

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pb push_back

using namespace std;
typedef pair<int, int> pii;
const int N = 2e5 + 5;
vector<pii> G[N];
int dp[N][2], W[N];

void dfs(int v, int p = -1){
	int ttl = 0;
	vector<int> ws;
	for(pii pa : G[v]){
		int i = pa.fi, w = pa.se;
		if(i == p) continue;
		W[i] = w;
		dfs(i, v);
		ws.push_back(w + dp[i][0] - dp[i][1]);
		ttl += dp[i][1];
	}
	sort(ws.begin(), ws.end(), greater<>());
	dp[v][0] = ttl;
	if(p != -1 && ws.size() >= 1) dp[v][1] = ttl + W[v] + ws[0];
	if(ws.size() >= 2) dp[v][0] = max(dp[v][0], ttl + ws[0] + ws[1]);
	dp[v][1] = max(dp[v][0], dp[v][1]);
}

int32_t main(){
	int n;
	cin >> n;
	for(int i = 0; i < n - 1; i++){
		int u, v, we;
		cin >> u >> v >> we;
		G[u].pb({v, we});
		G[v].pb({u, we});
	}
	dfs(1);
//	for(int i = 1; i <= n; i++){
//		cout << i << ": " << dp[i][0] << ' ' << dp[i][1] << endl;
//	}
	cout << max(dp[1][0], dp[1][1]) << endl;
}

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