poj 3264 Balanced Lineup（查询区间最

1.代码：

#include<stdio.h>
#include<string.h>
#include<math.h>
#define Max(a,b) ((a)>(b)?(a):(b))
#define Min(a,b) ((a)<(b)?(a):(b))
#define N 100000

int a[N];
int ST1[N][20];
int ST2[N][20];
int n,q;

void make_ST()
{
    for(int j=1;(1<<j)<=n;j++)
    {
        for(int i=1;(i+(1<<j)-1)<=n;i++)
        {
            ST1[i][j]=Max(ST1[i][j-1],ST1[i+(1<<(j-1))][j-1]);
            ST2[i][j]=Min(ST2[i][j-1],ST2[i+(1<<(j-1))][j-1]);
        }
    }
}

int Query(int l,int r)
{
    int k=floor(log((double)(r-l+1))/log((double)(2)));
    return Max(ST1[l][k],ST1[r-(1<<k)+1][k])-Min(ST2[l][k],ST2[r-(1<<k)+1][k]);
}

int main()
{
    while(scanf("%d%d",&n,&q)==2)
    {
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&a[i]);
            ST1[i][0]=ST2[i][0]=a[i];
        }
        make_ST();
        while(q--)
        {
            int l,r;
            scanf("%d%d",&l,&r);
            printf("%d
",Query(l,r));
        }
    }
    return 0;
}