Cod sursa(job #390937)

Utilizator mathboyDragos-Alin Rotaru mathboy Data 4 februarie 2010 20:26:23
Problema Stramosi Scor 50
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.24 kb
#include <fstream>
#include <vector>
#include <bitset>
#define DIM 250005
#define pb push_back

using namespace std;

ifstream fin ("stramosi.in"); // citire + scriere cu streamuri pt eficienta (cica)
ofstream fout ("stramosi.out");
struct tip
{
        unsigned int x:19;
}__attribute__ ((packed));

int N, M, i, p, q , a;
tip st [DIM];

vector <int> sol [DIM], G [DIM];
bitset <DIM>viz;

void dfs (int node, int lev) {
    
	int j;
	st [++lev].x = node;
	for (j = 0; j < G [node].size (); j++) 
		if (!viz [G [node][j]]) {
			viz [G [node][j]] = true;
			dfs (G [node][j], lev);
		}
	-- lev;
	for (int k = lev; k >= 1; k--)
		sol [node].pb (st [k].x);
}

int main () {
	
	int j, t;
	fin >> N >> M;
	for (i = 1; i <= N; i++) {
		fin >> a;
		G [a].pb (i);
	}
	for (i = 0; i <= N; i++)
		if (!viz [i])
			dfs (i, 0);
	for (i = 0; i <= N; i++) {
		vector <int>(G [i]).swap (G [i]);
		vector <int>(sol [i]).swap (sol [i]);
	}
	for (i = 1; i <= M; i++) 
	{
		fin >> q >> p;
		if (q >= DIM) fout << 0 << "\n";
		else
		{
			for (t = 0, j = 0; j < sol [q].size (); j++) 
			if (j == p - 1)
			{
				fout << sol [q][j] << "\n";
				t = 1;
				break;
			}
			if (t == 0) fout << 0 <<"\n";
		}
	}
	return 0;
}