Cod sursa(job #53517)

Utilizator chermanCorina Herman cherman Data 22 aprilie 2007 13:39:01
Problema Stramosi Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.63 kb
#include <stdio.h>
#include <iostream>
#include <math.h>

using namespace std;

int N[250000];
int a[250000][18];

FILE *in = fopen("stramosi.in", "r"), *out = fopen("stramosi.out", "w");
int n, m;

inline int findvlad(int nr, int times)
{
    if (times>n) return 0;
    nr = N[nr-1];
    //cout<<nr<<endl;
	for ( int i = times-1; i != 0; i-- )
	{
		if ( N[nr-1] == 0 )
			return 0;
		nr = N[nr-1];
	}

  return nr;
}

inline int findcorinarand(int nr, int times)
{
    if (times>n) return 0;
    int rand=log2(times);
    nr = N[nr-1];

    while (a[rand][nr-1]==-1) rand--;

 	for ( int i = pow(2,rand)+1;i<= times; i++ )
	{
	    int lg=(int)log2(i);

		if (i&(i-1)==0)//( lg==pow(2,i))
		{
		    if (a[lg][nr-1]==0) return 0;
		    else a[lg][nr-1]=nr;
		}
		nr = N[nr-1];
	}

  return nr;
}
inline int findcorinacol(int nr, int times)
{
    int col=log2(times);
    nr = N[nr-1];

    while (a[nr-1][col]==-1) col--;

 	for ( int i = pow(2,col)+1;i<= times; i++ )
	{
	    int lg=(int)log2(i);

		if (i&(i-1)==0)//( lg==pow(2,i))
		{
		    if (a[nr-1][lg]==0) return 0;
		    else a[nr-1][lg]=nr;
		}
		nr = N[nr-1];
	}

  return nr;
}



int main ()
{
	int temp1, temp2;

	fscanf(in, "%d %d", &n, &m);

	for ( int i = 0; i != n; ++i )
	{
		fscanf(in, "%d", &N[i]);
		a[i][0] = N[i];
		for ( int j = 1; j!= 18; ++j )
            a[i][j] = -1;
	}



	for ( int i = m-1; i != -1; --i )
	{

	    fscanf(in, "%d %d", &temp1, &temp2);
	    //fprintf(out, "%d\n", findvlad(temp1, temp2));
	    fprintf(out, "%d\n", findcorinacol(temp1, temp2));
     }



	return 0;
}