Submission #546212

#	Time	Username	Problem	Language	Result	Execution time	Memory
546212		Deepesson	Power Plant (JOI20_power)	C++17	100 / 100	885 ms	28324 KiB

power

#include <bits/stdc++.h>
#define MAX 205000
std::vector<int> con[MAX];
bool existe[MAX];
int dfs(int pos,int prev){
    int size=1;
    for(auto&x:con[pos]){
        if(x==prev||existe[x])continue;
        size+=dfs(x,pos);
    }
    return size;
}
int centroide;
int find_centroide(int pos,int prev,int sz){
    int size=1;
    int max=0;
    for(auto&x:con[pos]){
        if(x==prev||existe[x])continue;
        int b =find_centroide(x,pos,sz);
        size+=b;
        max=std::max(max,b);
    }
    max=std::max(max,sz-size);
    if(max<=sz/2)centroide=pos;
    return size;
}
std::string valores;
int explora(int pos,int prev){
    int ans=0;
    if(valores[pos]=='1')ans=1;
    int soma=0;
    for(auto&x:con[pos]){
        if(x==prev||existe[x])continue;
        soma+=explora(x,pos);
    }
    if(valores[pos]=='1')--soma;
    return std::max(ans,soma);
}
int N;
int ans=0;
void Decompor(int Y){
    int SZ = dfs(Y,-1);
    find_centroide(Y,-1,SZ);
    int CN = centroide;
   /// std::cout<<"Centro: "<<CN<<" "<<Y<<" "<<SZ<<"\n";
    existe[CN]=true;
    int tot=0;
    int ans2=0;
    for(auto&x:con[CN]){
        if(existe[x])continue;
        int b=explora(x,CN);
        tot+=b;
        if(valores[CN]=='1')ans2=std::max(ans2,b+1);
    }
    if(valores[CN]=='1'){
        --tot;
        tot=std::max(tot,1);
    }
    ans=std::max(ans,tot);
    ans=std::max(ans,ans2);
    for(auto&x:con[CN]){
        if(existe[x])continue;
        Decompor(x);
    }
}
int main()
{
    std::cin>>N;
    for(int i=1;i!=N;++i){
        int a,b;
        std::cin>>a>>b;
        --a;--b;
        con[a].push_back(b);
        con[b].push_back(a);
    }
    std::cin>>valores;
    Decompor(0);
    std::cout<<ans<<"\n";
}

• Subtask 1: 6 / 6
• Subtask 2: 41 / 41
• Subtask 3: 53 / 53