Submission #751998

#	Time	Username	Problem	Language	Result	Execution time	Memory
751998		boyliguanhan	Beads and wires (APIO14_beads)	C++17	0 / 100	4 ms	4968 KiB

beads

#include<bits/stdc++.h>
using namespace std;
long long dp[200100][2];
vector<pair<int, long long>> adj[200100];
void dfs(int n, int p) {
    dp[n][0] = 0;
    dp[n][1] = -1e18;
    long long m1=-1e18, m2=-1e18;
    for(auto [i, j]: adj[n]) {
        if(i!=p) {
            dfs(i, n);
            long long X = max(dp[i][1]+j, dp[i][0]);
            dp[n][0]+=X;
            long long x = dp[i][0] + j - X;
            if(m1 <= x)m2 = m1, m1 = x;
            else if(m2<x) m2 = x;
        }
    }
    dp[n][1]=dp[n][0]+m1;
    dp[n][0]+=max(0LL,m1+m2);
}
int main() {
    cin.sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    for(int i = 1; i < n; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        adj[a].push_back({b, c});
        adj[b].push_back({a, c});
    }
    long long m = -1e18;
    for(int i = 1; i <= n; i++) {
        dfs(i, 0);
        m = max(m, dp[i][0]);
    }
    cout << m << '\n';
}

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