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Cod sursa(job #390937)
#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;
}