【模板】ST表

#include <cstdio>
#include <cmath>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

int n, m, f[100010][21];

void init()
{
    for (int j = 1; j <= 20; j++)
        for (int i = 1; i + (1 << j) - 1 <= n; i++)
            f[i][j] = max(f[i][j - 1],f[i + (1 << (j - 1))][j - 1]);
}

int main()
{
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++)
        scanf("%d", &f[i][0]);
    init();
    for (int i = 1; i <= m; i++)
    {
        int l, r, t;
        scanf("%d%d", &l, &r);
        t = (int)((log(r - l + 1)) / log(2.0));
        printf("%d
", max(f[l][t], f[r - (1 << t) + 1][t]));
    }

    return 0;
}