Cod sursa(job #2707327)

Utilizator hhhhhhhAndrei Boaca hhhhhhh Data 16 februarie 2021 20:00:13
Problema Stramosi Scor 90
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.99 kb
#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
ifstream fin("stramosi.in");
ofstream fout("stramosi.out");
int n,m,v[250005],dp[250005][21];
vector<int> muchii[250005];
void dfs(int nod, int parent)
{
    dp[nod][0]=parent;
    for(int i=1;i<=18;i++)
        dp[nod][i]=dp[dp[nod][i-1]][i-1];
    for(auto i:muchii[nod])
        dfs(i,nod);
}
int query(int nod,int val)
{
    int p=nod;
    for(int i=0;i<=18&&val>0;i++)
        if((val>>i)&1)
        {
            p=dp[p][i];
            val-=(1LL<<i);
        }
    return p;
}
int main()
{
    ios_base::sync_with_stdio(false);
    fin.tie(0);
    fout.tie(0);
    fin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        int a;
        fin>>a;
        v[i]=a;
        muchii[a].push_back(i);
    }
    for(int i=1;i<=n;i++)
        if(v[i]==0)
            dfs(i,0);
    while(m--)
    {
        int nod,val;
        fin>>nod>>val;
        fout<<query(nod,val)<<'\n';
    }
    return 0;
}