Submission #218343

#	Time	Username	Problem	Language	Result	Execution time	Memory
218343		Autoratch	Beads and wires (APIO14_beads)	C++14	13 / 100	8 ms	5120 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][6];

int mxx(int a,int b,int c,int d){ return max(max(a,d),max(b,c)); }

void dfs(int u,int p)
{
    int all = 0,mx = INT_MIN,mx2 = INT_MIN,mxc = INT_MIN,cn = 0;
    dp[u][1] = INT_MIN,dp[u][2] = INT_MIN,dp[u][4] = INT_MIN,dp[u][5] = INT_MIN;
    for(auto [d,v] : adj[u]) if(v!=p)
    {
        dfs(v,u);
        int each = mxx(dp[v][0],dp[v][2],dp[v][3],dp[v][4]);
        all+=each,cn+=max(each,d+dp[v][1]);
        dp[u][1] = max(dp[u][1],d+max(dp[v][0],dp[v][2])-max(each,d+dp[v][1]));
        int tmp = d+max(dp[v][0],dp[v][2])-max(each,d+dp[v][1]);
        if(tmp>mx) mx2 = mx,mx = tmp;
        else if(tmp>mx2) mx2 = tmp;
        mxc = max(mxc,d+max(dp[v][3],dp[v][4])-max(each,d+dp[v][1]));
        dp[u][4] = max(dp[u][4],d+dp[v][5]-max(each,d+dp[v][1]));
        dp[u][5] = max(dp[u][5],d+max(dp[v][3],dp[v][4])-max(each,d+dp[v][1]));
    }
    dp[u][0] = all;
    dp[u][1]+=cn;
    dp[u][2] = cn;
    if(mx==INT_MIN or (mx2==INT_MIN and mxc==INT_MIN)) dp[u][3] = INT_MIN;
    else dp[u][3] = mx+max(mx2,mxc)+cn;
    dp[u][4]+=cn;
    dp[u][5]+=cn;
}

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 << mxx(dp[1][0],dp[1][2],dp[1][3],dp[1][4]);
}

Compilation message (stderr)

beads.cpp: In function 'void dfs(int, int)':
beads.cpp:16:14: warning: decomposition declaration only available with -std=c++1z or -std=gnu++1z
     for(auto [d,v] : adj[u]) if(v!=p)
              ^

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