Submission #218126

#	Time	Username	Problem	Language	Result	Execution time	Memory
218126		Autoratch	Beads and wires (APIO14_beads)	C++14	0 / 100	7 ms	4992 KiB

beads

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

const int N = 2e5 + 1;

int n;
vector<pair<int,int> > adj[N];
int dp[N][3];

void dfs(int u,int p)
{
    int mx = 0,mx2 = INT_MIN,s1 = 0;
    dp[u][1] = INT_MIN;
    for(auto [d,v] : adj[u]) if(v!=p)
    {
        dfs(v,u);
        dp[u][0]+=max(dp[v][0],dp[v][2]);
        if(dp[v][1]!=INT_MIN) s1+=dp[v][1]+d;
        if(dp[v][1]!=INT_MIN) dp[u][1] = max(dp[u][1],d+max(dp[v][0],dp[v][2])-dp[v][1]);
        else dp[u][1] = max(dp[u][1],d+max(dp[v][0],dp[v][2]));
        int tmp = max(max(dp[v][0],dp[v][2]),d+dp[v][1]);   
        dp[u][2]+=tmp;
        if(d+max(dp[v][0],dp[v][2])-tmp>mx) mx2 = mx,mx = d+max(dp[v][0],dp[v][2])-tmp;
        else if(d+max(dp[v][0],dp[v][2])-tmp>mx2) mx2 = d+max(dp[v][0],dp[v][2])-tmp;
    }
    dp[u][1]+=s1;
    dp[u][2]+=max(0,mx+mx2);
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);

    cin >> n;
    for(int i = 0;i < n-1;i++)
    {
        int a,b,d;
        cin >> a >> b >> d;
        adj[a].push_back({d,b});
        adj[b].push_back({d,a});
    }
    dfs(1,0);
    cout << max(dp[1][0],dp[1][2]);
}

Compilation message (stderr)

beads.cpp: In function 'void dfs(int, int)':
beads.cpp:14:14: warning: decomposition declaration only available with -std=c++1z or -std=gnu++1z
     for(auto [d,v] : adj[u]) if(v!=p)
              ^

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