Submission #957434

#	Time	Username	Problem	Language	Result	Execution time	Memory
957434		Haidara314	Race (IOI11_race)	C++17	100 / 100	387 ms	81748 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#define ll long long
#define F first
#define S second
using namespace std;
int ans=1e9;
ll k;
vector<pair<int,ll>>adj[200005];
ll dep[200005];
int dis[200005];
map<int,int> arr[200005];
void dfs(int u,int p)
{
    for(auto x:adj[u])
    {
        if(x.F!=p)
        {
            dep[x.F]=dep[u]+x.S;
            dis[x.F]=dis[u]+1;
            dfs(x.F,u);
            if(arr[x.F].size()>arr[u].size())
                swap(arr[x.F],arr[u]);
            for(auto f:arr[x.F])
            {
                int z=2*dep[u]+k-f.F;
                if(arr[u].count(z))
                {
                    ans=min(ans,arr[u][z]+f.S-2*dis[u]);
                }
            }
            for(auto g:arr[x.F])
            {
                if(arr[u][g.F])
                arr[u][g.F]=min(arr[u][g.F],g.S);
                else
                    arr[u][g.F]=g.S;
            }
        }
    }
    if(arr[u].count(dep[u]+k))
        ans=min(ans,arr[u][dep[u]+k]-dis[u]);
    arr[u][dep[u]]=dis[u];
}
int best_path(int N, int K, int H[][2], int L[])
{
 k=K;
 for(int i=0;i<N-1;i++)
 {
     adj[H[i][0]].push_back({H[i][1], L[i]});
		adj[H[i][1]].push_back({H[i][0], L[i]});
 }
 dfs(0,0);
  if(ans==1e9)
    ans=-1;
  return ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 57 / 57