Cod sursa(job #2062390)

Utilizator savigunFeleaga Dragos-George savigun Data 10 noiembrie 2017 12:19:28
Problema Range minimum query Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 1 kb
#include <iostream>
#include <fstream>
using namespace std;

ifstream in("rmq.in");
ofstream out("rmq.out");

const int MAXN = 1e5 + 5;
int n, m, v[MAXN], lg[MAXN];
int dp[17][MAXN];

void compute() {
    int next = 2;
    for (int i = 1; i <= n; ++i) {
        lg[i] = lg[i - 1];
        if (i == next) {
            next *= 2;
            lg[i]++;
        }
    }

    for (int j = 1; j <= n; ++j) dp[0][j] = v[j];
    for (int i = 1; i <= 16; ++i) {
        int step = 1 << (i - 1);
        for (int j = 1; j <= n - step; ++j) {
            dp[i][j] = min(dp[i - 1][j], dp[i - 1][j + step]);
        }
    }
}

int query(int l , int r) {
    if (l > r) return 1e6;
    int s = r - l + 1;
    int p = lg[s];
    return min(dp[p][l], query(l + (1 << p), r));
}

int main()
{
    in >> n >> m;
    for (int i = 1; i <= n; ++i) in >> v[i];
    compute();

    for (int i = 1, l, r; i <= m; ++i) {
        in >> l >> r;
        out << query(l, r) << "\n";
    }

    return 0;
}