Pagini recente » Cod sursa (job #326814) | Cod sursa (job #981695) | Cod sursa (job #2230102) | Cod sursa (job #2979424) | Cod sursa (job #2308517)
#include <bits/stdc++.h>
using namespace std;
ifstream in("stramosi.in");
ofstream out("stramosi.out");
const int N = 250005;
const int L = 20;
int lvl[N],dp[L][N],n,lg[N];
vector<int> v[N], start;
void dfs(int x)
{
for (auto it: v[x])
{
if (!lvl[it])
{
lvl[it] = 1+lvl[x];
dfs(it);
dp[0][it] = x;
}
}
}
void buildDP()
{
for (int i = 2; i<=n; i++)
lg[i] = lg[i/2]+1;
for (int i = 1; (1<<i)<=n; i++)
for (int j = 1; j<=n; j++)
dp[i][j] = dp[i-1][dp[i-1][j]];
}
int query(int x, int p)
{
int dif = lvl[x]-p;
for (int i = lg[lvl[x]]+1; i>=0; i--)
if (lvl[x]-(1<<i)>=dif)
x = dp[i][x];
return x;
}
int main()
{
ios::sync_with_stdio(0);
in.tie(0);
out.tie(0);
int m;
in >> n >> m;
for (int i = 1; i<=n; i++)
{
int x;
in >> x;
if (!x)
start.push_back(i);
else
v[x].push_back(i);
}
for (auto it: start)
dfs(it);
buildDP();
for (int i = 1; i<=m; i++)
{
int x,p;
in >> x >> p;
out << query(x,p) << "\n";
}
}