Submission #935039

#	Time	Username	Problem	Language	Result	Execution time	Memory
935039		Darren0724	Beads and wires (APIO14_beads)	C++17	0 / 100	3 ms	9820 KiB

beads

#include <bits/stdc++.h>
using namespace std;
#define LCBorz ios_base::sync_with_stdio(false); cin.tie(0);
#define int long long
#define all(x) x.begin(), x.end()
#define endl '\n'
const int N=200005;
const int INF=1e18;
const int mod=998244353;
int n;
vector<pair<int,int>> adj[N];
vector dp(2,vector(N,(int)0));
void dfs(int k,int pa,int cost){
    vector<int> t;
    int cnt=0;
    for(auto [j,c]:adj[k]){
        if(j==pa)continue;
        dfs(j,k,c);
        t.push_back(dp[1][j]-dp[0][j]);
        cnt+=dp[0][j];
    }
    sort(all(t),greater<>());
    int sz=t.size();
    dp[0][k]=cnt;
    dp[1][k]=cnt+cost;
    if(sz>=1){
        int tmp=cnt+t[0];
        dp[0][k]=max(dp[0][k],tmp+cost);
    }
    if(sz>=2){
        int tmp=cnt+t[0]+t[1];
        dp[0][k]=max(dp[0][k],tmp);
        dp[1][k]=max(dp[1][k],tmp+cost);
    }
}

int32_t main() {
    LCBorz;
    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});
    }
    dfs(1,1,-INF);
    cout<<dp[0][1]<<endl;
    
    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