Submission #411606

#	Time	Username	Problem	Language	Result	Execution time	Memory
411606		A_D	Race (IOI11_race)	C++14	9 / 100	2023 ms	128528 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#define LL long long
#define ii pair<LL,LL>
#define F first
#define S second
using namespace std;
const int NN=2e5+100;
vector<ii> g[NN];
int dp[NN][111];
LL n,k;
int ans=1e9;
multiset<int> st;
void dfs(int u,int p)
{
    dp[u][0]=0;
    for(auto x:g[u]){
        if(x.F==p)continue;
        dfs(x.F,u);
    }
    for(auto x:g[u]){
        if(x.F==p)continue;
        for(int i=0;i<=k;i++){
            if(i-x.S>=0)dp[u][i]=min(dp[x.F][i-x.S]+1,dp[u][i]);
        }
    }
    if((g[u].size()==2&&u!=p)||g[u].size()==1)return;
    for(int i=0;i<=k;i++){
//        cout<<i<<" ";
        st.clear();
        for(auto x:g[u]){
            if(x.F==p)continue;
            if(i-x.S>=0)st.insert(dp[x.F][i-x.S]);
        }
        for(auto x:g[u]){
            if(x.F==p)continue;
            if(i-x.S>=0)st.erase(st.find(dp[x.F][i-x.S]));
            int j=(k-i)-x.S;
            if(j>=0){
                int ret=*st.begin();
  //              cout<<ret<<" ";
                ret+=dp[x.F][j];
    //            cout<<dp[x.F][j]<<endl;
                ans=min(ans,ret+2);
            }
            if(i-x.S>=0)st.insert(dp[x.F][i-x.S]);
        }
//        cout<<endl;
    }
}
int best_path(int N, int K, int H[][2], int L[])
{
    ans=1e9;
    n=N;
    k=K;
    for(int i=0;i<n;i++){
        for(int j=0;j<=k;j++){
            dp[i][j]=1e9;
        }
    }
    for(int i=0;i<n-1;i++){
        int u=H[i][0];
        int v=H[i][1];
        int w=L[i];
        g[u].push_back({v,w});
        g[v].push_back({u,w});
    }
    dfs(0,0);
    /*
    cout<<endl;
    for(int i=0;i<n;i++){
        for(int j=0;j<=k;j++){
            cout<<dp[i][j]<<" ";
        }
        cout<<endl;
    }
    cout<<endl;
    */
    for(int i=0;i<n;i++){
        ans=min(ans,dp[i][k]);
    }
    if(ans==1e9)ans=-1;
    return ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57