POJ 3264 Balanced Lineup | st表

题意:

求区间max-min

st表模板

 #include<cstdio>
 #include<algorithm>
 #include<cstring>
 #include<cmath>
 #define N 50010
 using namespace std;
 int rmin[N][],rmax[N][],n,l,r,q;
 int read()
 {
     int ret=,neg=;
     char j=getchar();
     for (;j>'' || j<'';j=getchar())
     if (j=='-') neg=-;
     for (;j<='' && j>='';j=getchar())
     ret=ret*+j-'';
     return ret*neg;
 }
 int main()
 {
     n=read(),q=read();
     for (int i=,x;i<=n;i++)
     x=read(),rmin[i][]=x,rmax[i][]=x;
     for (int j=;j<=;j++)
     for (int i=;i+(<<j)-1<=n;i++)
         rmin[i][j]=min(rmin[i][j-],rmin[i+(<<j-)][j-]),rmax[i][j]=max(rmax[i][j-],rmax[i+(<<j-)][j-]);
     while (q--)
     {
     l=read(),r=read();
     int lg=log2(r-l+);
     printf("%d\n",max(rmax[l][lg],rmax[r-(<<lg)+][lg]) - min(rmin[l][lg],rmin[r-(<<lg)+][lg]));
     }
     return ;
 }