Cod sursa(job #3177218)

Utilizator Cristi3956Pop Cristian Cristi3956 Data 28 noiembrie 2023 18:43:02
Problema Range minimum query Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.13 kb
#include <fstream>

#define NMAX 100001
#define LMAX 17
// 2^17 = 131072

using namespace std;

ifstream fin("rmq.in");
ofstream fout("rmq.out");
int n, i, a[NMAX], m[LMAX][NMAX], s, d, q, lu, lg[NMAX], l;

void dina()
{
    int c, l;
    
    for (c = 1; c <= n; c++)
        m[0][c] = a[c];
    for (l = 1; (lu = (1 << l) <= n); l++) // Minimele pentru secvente de lungime 2^l.
        for (c = 1; c + (lu - 1) <= n; c++)
            m[l][c] = min(m[l - 1][c], m[l - 1][c + lu / 2]);
}

/*
    c   v
....----||||.....
    x      
          
123456789012345678901234567890
         -----------
         ........
            |.......
          

*/

int main()
{
    fin >> n >> q;
    for (i = 1; i <= n; i++)
        fin >> a[i];
    dina();
    lg[1] = 0;
    for (i = 2; i <= n; i++)   // [log2 i]
        lg[i] = lg[i / 2] + 1; // log2 (i / 2) + log2 2 = log2 (i / 2 * 2) = log2 i
    for (i = 1; i <= q; i++)
    {
        fin >> s >> d;
        lu = d - s + 1;
        l = lg[lu]; // linia din care luam informatiile
        fout << min (m[l][s], m[l][d - (1 << l) + 1]) << '\n';
    }
    return 0;
}