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Cod sursa(job #677371)
#include <fstream>
#include <vector>
#include <stack>
using namespace std;
#define NSIZE 250001
#define MSIZE 300001
const char* infile = "stramosi.in";
const char* outfile = "stramosi.out";
vector<int> G[NSIZE];
vector<pair<int, int> > Intrebari[NSIZE];
int Solutii[MSIZE];
bool viz[NSIZE];
vector<int> stramosi;
void DFS(int root)
{
stack<int> stiva;
stiva.push(root);
while(stiva.empty() == false)
{
int current = stiva.top();
if(viz[current] == true)
{
stiva.pop();
stramosi.pop_back();
continue;
}
viz[current] = true;
stramosi.push_back(current);
for(unsigned int i = 0; i < G[current].size(); ++i)
{
stiva.push(G[current][i]);
}
for(vector<pair<int, int> > ::iterator itr = Intrebari[current].begin();
itr != Intrebari[current].end();
itr++)
{
int P = itr->first;
int index = itr->second;
int raspuns = ((unsigned) P > stramosi.size() - 1 ) ? 0 : stramosi[stramosi.size() - 1 - P ];
Solutii[index] = raspuns;
}
}
}
int main()
{
fstream fin(infile, ios::in);
fstream fout(outfile, ios::out);
int N, M;
fin >> N >> M;
for(int i = 0 ; i < N; i++)
{
int parinte;
fin >> parinte;
G[parinte].push_back(i+1);
}
for(int i = 0 ; i < M; i++)
{
int Q, P;
fin >> Q >> P;
Intrebari[Q].push_back(make_pair(P, i));
}
DFS(0);
for(int i = 0 ; i < M; i++)
{
fout << Solutii[i] << "\n";
}
fin.close();
fout.close();
}