Submission #670786

#	Time	Username	Problem	Language	Result	Execution time	Memory
670786		Arnch	Beads and wires (APIO14_beads)	C++17	0 / 100	2 ms	2644 KiB

beads

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

#define Sz(x) (x).size()

const int N = 1e5 + 10;

long long dp[N][2];
vector<pair<int, int> > adj[N];

void DFS(int x, int p = 0, int cnt = 0) {
    for(auto [j, t] : adj[x]) {
        if(j == p) continue;
        DFS(j, x, t);
    }
    if(Sz(adj[x]) == 1 && x != 1) {
        return;
    }
    long long sum = 0;
    for(auto [j, t] : adj[x]) {
        if(j == p) continue;
        sum += dp[j][1];
    }
    dp[x][0] = sum;
    vector<int> vc;
    for(auto [j, t] : adj[x]) {
        if(j == p) continue;
        vc.push_back(dp[j][0] + t - dp[j][1]);
    }
    sort(vc.begin(), vc.end(), greater<int>());
    if(vc.size() > 1) {
        dp[x][0] = max(dp[x][0], sum + vc[0] + vc[1]);
    }
    dp[x][1] = dp[x][0];
    if(vc.size() > 0) {
        dp[x][1] = max(dp[x][1], sum + vc[0] + cnt);
    }
}

int main() {
    int n; cin >>n;
    for(int i = 0; i < n - 1; i++) {
        int u, v, c; cin >>u >>v >>c;
        adj[u].push_back({v, c}), adj[v].push_back({u, c});
    }

    DFS(1);

	cout<<dp[1][0];
}

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