Submission #719204

#	Time	Username	Problem	Language	Result	Execution time	Memory
719204		HunterXD	Race (IOI11_race)	C++17	21 / 100	3074 ms	19464 KiB

race

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

int n,k,tam[200005],lv[200005],vis[200005],ans=1e9,val[1000005];
vector<pair<int,int> > adj[200005];
 
void tamanio_tree(int u,int p){
    tam[u]=1;
    for(auto [node,w]:adj[u]){
        if(vis[node]==0&&node!=p){
            tamanio_tree(node,u);
            tam[u]+=tam[node];
        }
    }
}
int centroid_descomposition(int u,int p,int want){
    for(auto [node,w]:adj[u]){
        if(node!=p&&vis[node]==0){
            if(tam[node]>want)return centroid_descomposition(node,u,want);
        }
    }
    return u;
}
 
void dfs(int u,int p,int depth,int lv,int type){
    if(depth>k)return;
    if(type==1){
        ans=min(ans,lv+val[k-depth]);
    }else if(type==0){
        val[depth]=min(val[depth],lv);
    }else{
        val[depth]=1e9,val[k-depth]=1e9;
    }
    for(auto [node,w]: adj[u]){
        if(node!=p&&vis[node]==0) {
            dfs(node,u,depth+w,lv+1,type);
        }
    }
}
 
void all_trees(int u){
    tamanio_tree(u,u);
    int c = centroid_descomposition(u,u,n/2);
    vis[c] = 1;
 
    for(auto [v,w] : adj[c]){
        if(!vis[v]){
            dfs(v,v,w,1,2);
        }
    }
    val[0] = 0;
 
    for(auto [v,w] : adj[c]){
        if(!vis[v]){
            dfs(v,v,w,1,1);
            dfs(v,v,w,1,0);
        }
    }
 
    for(auto [v,w] : adj[c]){
        if(!vis[v]){
            all_trees(v);
        }
    }
}
 
int best_path(int N, int K, int H[][2], int L[]){
    n = N, k = K;
    for(int i=0;i<n-1;i++){
        adj[H[i][0]+1].push_back({H[i][1]+1,L[i]});
        adj[H[i][1]+1].push_back({H[i][0]+1,L[i]});
    }
    for(int i=1;i<=n;i++){
        vis[i]=0;
    }
    for(int i=1;i<=1000000;i++){
        val[i] = 1e9;
    }
    all_trees(1);
    return (ans == 1e9) ? -1 : ans;
}

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