Cod sursa(job #2283098)

Utilizator TooHappyMarchitan Teodor TooHappy Data 14 noiembrie 2018 23:24:27
Problema Stramosi Scor 80
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.17 kb
#include <bits/stdc++.h>
 
using namespace std;
 
ifstream in("stramosi.in");
ofstream out("stramosi.out");

vector< vector< int > > stramos;

int getStramos(int q, int p) {
    if(p == 0) {
        return q;
    }

    if(q < 1) {
        return 0;
    }

    int pwr = log2(p);
    return getStramos(stramos[q][pwr], p - (1 << pwr));
}

int main() {
    ios::sync_with_stdio(false); in.tie(0); out.tie(0);

    int n, m; in >> n >> m;

    stramos.resize(n + 1, vector< int >(20));
    for(int i = 1; i <= n; ++i) {
        int s; in >> s;
        if(s == 0) {
            stramos[i][0] = -1;
        } else {
            stramos[i][0] = s;
        }
    }

    for(int j = 1; j < 18; ++j) {
        for(int i = 1; i <= n; ++i) {
            if(stramos[i][j - 1] != -1) {
                stramos[i][j] = stramos[stramos[i][j - 1]][j - 1];
            } else {
                stramos[i][j] = -1;
            }
        }
    }

    for(int i = 1; i <= m; ++i) {
        int q, p; in >> q >> p;

        int strm = getStramos(q, p);
        if(strm != -1) {
            out << strm << "\n";
        } else {
            out << "0\n";
        }
    }

    in.close(); out.close();
 
    return 0;
}