Cod sursa(job #3193928)

Utilizator Giulian617Buzatu Giulian Giulian617 Data 16 ianuarie 2024 09:45:23
Problema Stramosi Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.82 kb
#include<bits/stdc++.h>
using namespace std;
ifstream f("stramosi.in");
ofstream g("stramosi.out");
const int NMAX=250005,LOGMAX=20;
int n,m,Q,P,ancestor[LOGMAX][NMAX];
/// ancestor[i][j] = the 2^i ancestor of j
void binary_lifting()
{
    for(int i=1; i<LOGMAX; i++)
        for(int j=1; j<=n; j++)
            ancestor[i][j]=ancestor[i-1][ancestor[i-1][j]];
}
int find_ancestor(int node,int no_ancestor)
{
    if(no_ancestor>=(1<<LOGMAX))
        return 0;
    for(int i=0; i<LOGMAX; i++)
        if(no_ancestor&(1<<i))
            node=ancestor[i][node];
    return node;
}
int main()
{
    f>>n>>m;
    for(int i=1; i<=n; i++)
        f>>ancestor[0][i];/// parent of i
    binary_lifting();
    for(int i=1; i<=m; i++)
    {
        f>>Q>>P;
        g<<find_ancestor(Q,P)<<'\n';
    }
    return 0;
}