Submission #537224

#	Time	Username	Problem	Language	Result	Execution time	Memory
537224		Leonardo_Paes	Beads and wires (APIO14_beads)	C++17	0 / 100	1 ms	468 KiB

beads

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
#define f first
#define s second
const int maxn = 1e4+10, inf = 0x3f3f3f3f;

vector<pii> grafo[maxn];
int dp[maxn][2];

// edg + dp[id][0] - dp[id][1];

void solve(int u, int p = 0, int e = -1){
	int sum = 0, sons = 0;
	int mx[2] = {-inf, -inf};
	for(pii vv : grafo[u]){
		int v = vv.f, w = vv.s;
		if(v == p) continue;
		sons++;
		solve(v, u, w);
		int aux = w + dp[v][0] - dp[v][1];
		mx[1] = max(mx[1], aux);
		if(mx[0] < mx[1]) swap(mx[0], mx[1]);
		sum += dp[v][1];
	}
	if(sons >= 2) dp[u][0] = sum + mx[0] + mx[1];
	else dp[u][0] = max(dp[grafo[u][0].f][0], dp[grafo[u][0].f][1]);
	if(e != -1 and mx[0] != -inf) dp[u][1] = e + sum + mx[0];
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
	int n;
	cin >> n;
	for(int i=1; i<n; i++){
		int u, v, w;
		cin >> u >> v >> w;
		grafo[u].push_back({v, w});
		grafo[v].push_back({u, w});
	}
	int ans = 0;
	for(int i=1; i<=n; i++){
		solve(i);
		ans = max(ans, dp[i][0]);
		//for(int j=1; j<=n; j++) cout << dp[j][0] << " " << dp[j][1] << "\n";
		for(int j=1; j<=n; j++) dp[j][0] = dp[j][1] = 0;
	}
	cout << ans << "\n";
	return 0;
	/*
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/
}

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