Cod sursa(job #1329075)

Utilizator livliviLivia Magureanu livlivi Data 29 ianuarie 2015 00:04:18
Problema Stramosi Scor 80
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.02 kb
#include<cstdio>
#define MAX 250000
using namespace std;

int dist[MAX+1];
int t[MAX+1][19];
int n;


int pas;


void build(){
    int i,j;

    for(i=1;(1<<i)<=n;i++)
        for(j=1;j<=n;j++)
            t[j][i]=t[t[j][i-1]][i-1];
}


void init(){
    int i,p;
    for(i=1;i<=n;i++)
        for(p=1;p<=18;p++) t[i][p]=-1;
}


int query(int ad,int x){
    if (ad>dist[x]) return 0;
    if (ad==0) return x;

    while((1<<pas)>ad) pas--;

    return query(ad-(1<<pas),t[x][pas]);
}


int parinte(int x){
    if (dist[x]!=0) return dist[x];
    if (t[x][0]==0) return 0;

    dist[x]=parinte(t[x][0])+1;
    return dist[x];
}


int main(){
    freopen ("stramosi.in","r",stdin);
    freopen ("stramosi.out","w",stdout);
    int i,m,p,q;

    scanf ("%d%d",&n,&m);
    for(i=1;i<=n;i++)
        scanf ("%d",&t[i][0]);


    init();

    for(i=1;i<=n;i++)
        if (dist[i]==0) dist[i]=parinte(i);

    build();

    for(i=1;i<=m;i++){
        scanf ("%d%d",&q,&p);
        pas=18;
        printf ("%d\n",query(p,q));
    }

    return 0;
}