RMQ-ST求区间最值

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <cstring>
 4 #include <string>
 5 #include <cstdio>
 6 #include <cmath>
 7 #define MAXN 2222222
 8 #define MAXM 11111
 9 #define lch(x) x<<1
10 #define rch(x) x<<1|1
11 #define lson l,m,rt<<1
12 #define rson m+1,r,rt<<1|1
13 using namespace std;
14 int mi[MAXN][22], mx[MAXN][22], w[MAXN];
15 int n, q;
16 void rmqinit()
17 {
18     for(int i = 1; i <= n; i++) mi[i][0] = mx[i][0] = w[i];
19     int m = (int)(log(n * 1.0) / log(2.0));
20     for(int i = 1; i <= m; i++)
21         for(int j = 1; j <= n; j++)
22         {
23             mx[j][i] = mx[j][i - 1];
24             if(j + (1 << (i - 1)) <= n) mx[j][i] = max(mx[j][i], mx[j + (1 << (i - 1))][i - 1]);
25             mi[j][i] = mi[j][i - 1];
26             if(j + (1 << (i - 1)) <= n) mi[j][i] = min(mi[j][i], mi[j + (1 << (i - 1))][i - 1]);
27         }
28 }
29 int rmqmin(int l,int r)
30 {
31     int m = (int)(log((r - l + 1) * 1.0) / log(2.0));
32     return min(mi[l][m] , mi[r - (1 << m) + 1][m]);
33 }
34 int rmqmax(int l,int r)
35 {
36     int m = (int)(log((r - l + 1) * 1.0) / log(2.0));
37     return max(mx[l][m] , mx[r - (1 << m) + 1][m]);
38 }
39 int main()
40 {
41     scanf("%d", &n);
42     for(int i = 1; i <= n; i++) scanf("%d", &w[i]);
43     rmqinit();
44     int l, r;
45     scanf("%d",&q);
46     while(q--)
47     {
48         scanf("%d%d", &l, &r);
49         printf("%d\n", rmqmin(l, r));
50     }
51     return 0;
52 }