ST表模板

//静态区间最值
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
int ST[maxn][25];
int a[maxn];
void STinit(int n) {
    for (int i = 1; i <= n; i++) {
        ST[i][0] = a[i];
    }
    for (int j = 1; (1 << j) <= n; j++) {
        for (int i = 1; i + (1 << j) - 1 <= n; i++) {
            ST[i][j] = max(ST[i][j - 1] , ST[i + (1 << (j - 1))][j - 1]);
        }
    }
}
int query(int l, int r) {
    int k = (int)(log((double)(r - l + 1)) / log(2.0));//转为以2为底数
    return max(ST[l][k], ST[r - (1 << k) + 1][k]);
}
int main() {
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        scanf("%d", &a[i]);
    }
    STinit(n);
    while (m--) {
        int l, r;
        scanf("%d%d", &l, &r);
        printf("%d\n", query(l, r));
    }
}

来源：https://www.cnblogs.com/ucprer/p/12274695.html