洛谷P3865ST表

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#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath> 
#define re register
using namespace std ;

int n , m , a[100005] , l , r ;
int f[10000010][21] ;

inline int read () {
    int f = 1 , x = 0 ; 
    char ch = getchar () ;
    while(ch > '9' || ch < '0') {if(ch == '-') f = -1 ; ch = getchar () ;}
    while(ch >= '0' && ch <= '9') {x = (x << 1) + (x << 3) + ch - '0' ; ch = getchar () ;}
    return x * f ;
}

inline void st(int x) {
    for(re int i = 1 ; i <= 21 ; ++ i) 
        for(re int j = 1 ; j + (1 << i) <= x + 1 ; ++ j)
            f[j][i] = max(f[j][i - 1] , f[j + (1 << (i -1))][i - 1]) ;
}

inline int query(int l , int r) {
    int k = log2(r - l + 1) ;
    return max(f[l][k] , f[r - (1 << k) + 1][k]) ;
}

int main () {
    n = read () ; m = read () ;
    for(re int i = 1 ; i <= n ; ++ i) {
        f[i][0] = read () ;
    }
    st(n) ;
    for(re int i = 1 ; i <= m ; ++ i) {
        l = read () ; r = read () ;
        printf("%d\n" , query(l , r)) ;
    }
    return 0 ;
}