Cod sursa(job #2222085)

Utilizator andreistanStan Andrei andreistan Data 16 iulie 2018 14:22:42
Problema Range minimum query Scor 10
Compilator cpp Status done
Runda Arhiva educationala Marime 0.9 kb
#include <iostream>
#include <fstream>
using namespace std;
ifstream f("rmq.in");
ofstream g("rmq.out");

int N, M;
int D[20][100001];

void precalc()
{
    for(int i = 1; i <= N; i++)
    {
        int bound = N - (1 << i) + 1; // N - 2^j + 1
        for(int j = 1; j <= bound; j++)
            D[i][j] = min(D[i - 1][j], D[i - 1][j + (1 << (i - 1))]);
    }
}

int RMQ(int x, int y)
{
    //RMQ(x,y)=min(D[k][x],D[k][y - 2^k + 1])
    //2^k <= y-x, k maxim
    int dif = y - x;
    int k = 0;
    for(; 1 << k <= dif; k++);
    k--;
    return min(D[k][x], D[k][y - (1 << k) + 1]);
}

int main()
{
    f >> N >> M;
    for(int i = 1; i <= N; i++)
        f >> D[0][i];
    precalc();
    while(M--)
    {
        int x, y;
        f >> x >> y;
        if(x != y)
            g << RMQ(x, y) << '\n';
        else
            g << D[0][x] << '\n';
    }
    return 0;
}