Cod sursa(job #3273059)

Utilizator AlexPlesescuAlexPlesescu AlexPlesescu Data 1 februarie 2025 09:27:17
Problema Stramosi Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.09 kb
#include <bits/stdc++.h>

using namespace std;
#define pb push_back
const int N = 250005;

int n, m, root, a[N], up[N][23];
vector<int> g[N];

void dfs(int node, int p = 0) {
    up[node][0] = p;
    for (int i = 1; i <= 20; i++) {
        up[node][i] = up[up[node][i - 1]][i - 1];
    }
    for (auto it : g[node]) {
        if (it != p) {
            dfs(it, node);
        }
    }
}

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    freopen("stramosi.in", "r", stdin);
    freopen("stramosi.out", "w", stdout);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        if (!a[i]) {
            root = i;
        } else {
            g[i].pb(a[i]);
            g[a[i]].pb(i);
        }
    }
    for (int i = 1; i <= n; i++) {
        if (!a[i]) {
            dfs(i);
        }
    }
    while (m--) {
        int p, q;
        cin >> q >> p;
        int u = q;
        for (int k = 0; k < 20; k++) {
            if (p & (1ll << k)) {
                u = up[u][k];
            }
        }
        cout << u << '\n';
    }
}