Submission #964502

#	Time	Username	Problem	Language	Result	Execution time	Memory
964502		12345678	Beads and wires (APIO14_beads)	C++17	0 / 100	2 ms	6796 KiB

beads

#include <bits/stdc++.h>

using namespace std;

const int nx=2e5+5;

#define ll long long

ll n, u, v, w, dp[2][nx];
vector<pair<ll, ll>> d[nx];

void dfs(int u, int p, int pw)
{
    vector<int> df;
    for (auto [v, w]:d[u]) if (v!=p) dfs(v, u, w), dp[0][u]+=dp[1][v], df.push_back(w+dp[0][v]-dp[1][v]);
    sort(df.begin(), df.end());
    reverse(df.begin(), df.end());
    if (w!=-1&&df.size()>=1) dp[1][u]=max(dp[0][u], dp[0][u]+df[0]+pw);
    if (df.size()>=2) dp[0][u]=max(dp[0][u], dp[0][u]+df[0]+df[1]);
}

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<n; i++) cin>>u>>v>>w, d[u].push_back({v, w}), d[v].push_back({u, w});
    dfs(1, 1, -1);
    cout<<dp[0][1];
}
/*
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