Submission #1041799

#	Time	Username	Problem	Language	Result	Execution time	Memory
1041799		MMihalev	Beads and wires (APIO14_beads)	C++14	28 / 100	1042 ms	16116 KiB

beads

#include<iostream>
#include<algorithm>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<vector>
#include<queue>
#include<stack>
#include<tuple>
#include<set>
#include<map>
#include<random>
#include<chrono>
using namespace std;
const int MAX_N=2e5+4;
const int INF=2e9+1e8;
int dp[MAX_N][2];
vector<int>pref[MAX_N];
vector<int>suf[MAX_N];
int n;
vector<pair<int,int>>g[MAX_N];
void reset()
{
    for(int i=1;i<=n;i++)
    {
        pref[i].clear();
        suf[i].clear();
        dp[i][0]=0;
        dp[i][1]=-INF;
    }
}
void dfs(int u,int par)
{
    int ch=0;

    for(auto [v,edge]:g[u])
    {
        if(v==par)continue;
        ch++;
        dfs(v,u);

        pref[u].push_back(max(edge+dp[v][1],dp[v][0]));
    }

    suf[u]=pref[u];
    for(int i=1;i<ch;i++)
    {
        pref[u][i]+=pref[u][i-1];
    }
    for(int i=ch-2;i>=0;i--)
    {
        suf[u][i]+=suf[u][i+1];
    }

    int i=0;
    for(auto [v,edge]:g[u])
    {
        if(v==par)continue;

        dp[u][1]=max(dp[u][1],(i-1>=0 ? pref[u][i-1] : 0)+(dp[v][0]+edge)+(i+1<ch ? suf[u][i+1] : 0));
        i++;
    }

    if(pref[u].size())dp[u][0]=pref[u].back();
}
signed main ()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    cin>>n;
    for(int i=1;i<n;i++)
    {
        int u,v,c;
        cin>>u>>v>>c;
        g[u].push_back({v,c});
        g[v].push_back({u,c});
    }
    int ans=0;
    for(int i=1;i<=n;i++)
    {
        reset();
        dfs(i,0);
        ans=max(ans,dp[i][0]);
    }
    cout<<ans<<"\n";
    return 0;
}

Compilation message (stderr)

beads.cpp: In function 'void dfs(int, int)':
beads.cpp:36:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   36 |     for(auto [v,edge]:g[u])
      |              ^
beads.cpp:56:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   56 |     for(auto [v,edge]:g[u])
      |              ^

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