[POJ] 3264 Balanced Lineup [ST算法]

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<math.h>
 4 #include<ctype.h>
 5 #include<stdlib.h>
 6 #include<stdbool.h>
 7 
 8 #define rep(i,a,b)      for(i=(a);i<=(b);i++)
 9 #define clr(x,y)        memset(x,y,sizeof(x))
10 #define sqr(x)          (x*x)
11 #define LL              long long
12 
13 int i,j,n,m,x,y,q,maxn,minn,
14     d[51000][50],f[51000][50];
15 
16 int min(int a,int b)
17 {
18     if(a<b) return a;
19     return b;
20 }
21 
22 int max(int a, int b)
23 {
24     if(a>b) return a;
25     return b;
26 }
27 
28 int RMQ_init()
29 {
30     int i;
31     
32     for(j=1;(1<<j)<=n;j++)
33         for(i=1;i+(1<<j)-1<=n;i++) {
34         d[i][j]=min(d[i][j-1],d[i+(1<<(j-1))][j-1]);
35         f[i][j]=max(f[i][j-1],f[i+(1<<(j-1))][j-1]);
36     }
37 }
38 
39 int RMQ(int L,int R)
40 {
41     int k=0;
42     
43     while(1<<(k+1)<=R-L+1) k++;
44     minn=min(d[L][k],d[R-(1<<k)+1][k]);
45     maxn=max(f[L][k],f[R-(1<<k)+1][k]);
46 }
47 
48 int main()
49 {
50     int i;
51     
52     clr(d,3); 
53     clr(f,-1); 
54     scanf("%d%d",&n,&q);
55     rep(i,1,n) {
56         scanf("%d",&d[i][0]);
57         f[i][0]=d[i][0];
58     }
59 
60     RMQ_init();
61     
62     while(q--) {
63         scanf("%d%d",&x,&y);
64         RMQ(x,y);
65         printf("%d\n",maxn-minn);
66     }
67     
68     return 0;
69 }