Submission #982389

#	Time	Username	Problem	Language	Result	Execution time	Memory
982389		Godgift42	Race (IOI11_race)	C++17	0 / 100	1 ms	2396 KiB

race

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


vector<vector<pair<int,int>>> adj;
int n, k;
vector<int> subtr;
vector<bool> vis;
unordered_map<int,int> mp1;
unordered_map<int,int>mp2;
int ans=INT_MAX;

void findsize(int u, int p){
    subtr[u]=1;
    for(auto [v,w]:adj[u]){
        if(v!=p and !vis[v]){
            findsize(v,u);
            subtr[u]+=subtr[v];
        }
    }
}

int findcentroid(int u, int p, int sz){
    for(auto [v,w]:adj[u]){
        if(v!=p and !vis[v] and subtr[v]>sz/2)return findcentroid(v,u,sz);
    }
    return u;
}

void dfs1(int u, int p, int dist, int depth, int cnt){
    if(dist>k)return;
    if((mp1[k-dist] and mp2[k-dist]==cnt) or k==dist) ans=min(ans,mp1[k-dist]+depth);
    for(auto [v,w]:adj[u]){
        if(v!=p and !vis[v]){
            dfs1(v,u,dist+w,depth+1,cnt);
        }
    }
}

void dfs2(int u, int p, int dist, int depth,int cnt){
    if(dist>k)return;
    if(mp1[dist]==0){
        mp1[dist]=depth;
        mp2[dist]=cnt;
    }
    else{
        if(mp2[dist]>cnt){
            mp1[dist]=depth;
            mp2[dist]=cnt;
        }
        else if(mp1[dist]>depth){
            mp1[dist]=depth;
            mp2[dist]=cnt;
        }
    }
    for(auto [v,w]:adj[u]){
        if(v!=p and !vis[v]){
            dfs2(v,u,dist+w,depth+1,cnt);
        }
    }
}

void buildcentroid(int u, int p, int cnt){
    findsize(u,u);
    int c=findcentroid(u,u,subtr[u]);
    vis[c]=true;
    mp2[0]=cnt;
    for(auto [v,w]:adj[c]){
        if(v!=p and !vis[v]){
            dfs1(v,c,w,1,cnt);
            dfs2(v,c,w,1,cnt);
        }
    }
    for(auto [v,w]:adj[c]){
        if(!vis[v])buildcentroid(v,c,cnt-1);
    }
}

int best_path(int N, int K, int H[][2], int L[]){
    n=N;
    k=K;
    adj.resize(n);
    subtr.resize(n);
    vis.resize(n);
    for(int i=0;i<n-1;i++){
        adj[H[i][1]].push_back({H[i][0],L[i]});
        adj[H[i][0]].push_back({H[i][1],L[i]});
    }
    buildcentroid(0,-1,n+1);
    if(ans==INT_MAX)return -1;
    return ans;
} 

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