Cod sursa(job #2977239)

Utilizator iProgramInCppiProgramInCpp iProgramInCpp Data 11 februarie 2023 09:51:20
Problema Stramosi Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.93 kb
#include <fstream>
using namespace std;
ifstream fin ("stramosi.in");
ofstream fout("stramosi.out");
#define NMAX 250001
#define LMAX 20

/**
T[i][j] : Al 2^j -lea stramos al nodului i.
*/
int T[NMAX][LMAX];
int n,m;

/// Query: Complexitate: ~log_2(n)
int query(int nod, int nivel)
{
    for (int j = LMAX - 1; j >= 0; j--)
    {
        if (nivel & (1 << j))
        {
            nod = T[nod][j];
        }
    }

    return nod;
}

int main()
{
    fin >> n >> m;
    for (int i=1; i<=n; i++)
    {
        fin >> T[i][0];
    }

    for (int j=1; j<LMAX; j++)
    {
        for (int i=1; i<=n; i++)
        {
            /// Al 2^j-lea stramos al nostru este al 2^(j-1)-lea stramos al stramosului 2^(j-1).
            T[i][j] = T[ T[i][j-1] ][j-1];
        }
    }

    for (int i=0; i<m; i++)
    {
        int a,b;
        fin >> a >> b;
        fout << query(a,b) << '\n';
    }

    return 0;
}