Cod sursa(job #3158243)

Utilizator octavian202Caracioni Octavian Luca octavian202 Data 18 octombrie 2023 09:24:11
Problema Stramosi Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.09 kb
#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

ifstream fin("stramosi.in");
ofstream fout("stramosi.out");

const int NMAX = 250003;

vector<int> g[NMAX];
int stramos[NMAX][20];
bool vis[NMAX];

void dfs(int nod) {
    vis[nod] = true;

    for (int p = 1; p <= 18; p++) {
        stramos[nod][p] = stramos[stramos[nod][p - 1]][p - 1];
    }

    for (auto fiu : g[nod]) {
        if (!vis[fiu]) {


            dfs(fiu);
        }
    }
}

int get_stramos(int nod, int u) {
    for (int p = 18; p >= 0; p--) {
        if ((1 << p) <= u) {
            u -= (1 << p);
            nod = stramos[nod][p];
        }
    }
    return nod;
}

int main() {

    int n, q;
    fin >> n >> q;
    for (int i = 1; i <= n; i++) {
        fin >> stramos[i][0];
        if (stramos[i][0] != 0) {
            g[stramos[i][0]].push_back(i);
        }
    }

    for (int i = 1; i <= n; i++) {
        if (!vis[i])
            dfs(i);
    }

    while (q--) {
        int u, v; // al u-lea stramos a lui v
        fin >> v >> u;

        fout << get_stramos(v, u) << '\n';
    }





    return 0;
}