Cod sursa(job #1951998)

Utilizator robertpop99Popescu Robert Gabriel robertpop99 Data 3 aprilie 2017 21:32:40
Problema Stramosi Scor 0
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.89 kb
#include <iostream>
#include <fstream>
#define nmax 250005
using namespace std;
int n,m,P[19][nmax];
int L[nmax];
int Log[nmax];
int ancestor(int nod, int y)
{
    int a;
    while(y>0)
    {
        a=Log[L[nod]-y-1];
        nod=P[a][nod];
        y-=(1<<a);

    }

    return nod;
}
int main()
{
    ifstream fin("stramosi.in");
    ofstream fout("stramosi.out");
    fin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        int x;
        fin>>x;
        P[0][i]=x;
        if(x==0) L[i]=0;
        else L[i]=L[x]+1;
    }
    for(int i=2;i<=n;i++)
        Log[i]=Log[i/2]+1;

    for(int j=1;(1<<j)<=n;j++)
        for(int i=1;i<=n;i++)
              P[j][i]=P[j-1][ P[i][j-1] ];
    for(int i=1;i<=m;i++)

        {
            int x,y;
            fin>>x>>y;
            fout<<ancestor(x,y)<<'\n';
        }
    fin.close();
    fout.close();
    return 0;
}