刷水题可耻

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cmath>
#include <utility>
#include <vector>
#include <queue>
#include <map>
#include <set>
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)>(y)?(y):(x))

using namespace std;

int a[50005],N,Q,l,r,f[50005][20],g[50005][20];

void RMQ_ST(int n, int a[])//f[i][j]=max(a[i..i+2^j-1])
{
    for(int i=1; i<=n; i++)
    {
        f[i][0]=a[i];
        g[i][0]=a[i];
    }
    int m=floor(log(n*1.0)/log(2.0));
    for(int j=1; j<=m; j++)
        for(int i=1; i<=n-(1<<j)+1; i++)
        {
            f[i][j]=max(f[i][j-1],f[i+(1<<(j-1))][j-1]);
            g[i][j]=min(g[i][j-1],g[i+(1<<(j-1))][j-1]);
        }
}
int main()
{
    scanf("%d%d",&N,&Q);
    for(int i=1; i<=N; i++)
        scanf("%d",&a[i]);
    RMQ_ST(N,a);
    for(int i=0; i<Q; i++)
    {
        scanf("%d%d",&l,&r);
        int k=floor(log((r-l+1)*1.0)/log(2.0));
        printf("%d\n",max(f[l][k],f[r-(1<<k)+1][k])-min(g[l][k],g[r-(1<<k)+1][k]));
    }
    return 0;
}