HDU 1754 I Hate It

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 200100;
18 int tree[maxn<<2],M;
19 void build(int n){
20     M = 1<<((int)log2(n)+1);
21     for(int i = M + 1; i <= M + n; i++)
22         scanf("%d",tree+i);
23     for(int i = M - 1; i > 0; --i)
24         tree[i] = max(tree[i<<1],tree[i<<1|1]);
25 }
26 void update(int n,int val){
27     for(tree[n += M] = val,n >>= 1; n; n >>= 1)
28         tree[n] = max(tree[n<<1],tree[n<<1|1]);
29 }
30 int query(int s,int t){
31     int maxv = -1;
32     s += M - 1;
33     t += M + 1;
34     while(s^t^1){
35         if(~s&1) maxv = max(maxv,tree[s^1]);
36         if(t&1) maxv = max(maxv,tree[t^1]);
37         s >>= 1;
38         t >>= 1;
39     }
40     return maxv;
41 }
42 int main() {
43     int n,m,a,b;
44     char s[6];
45     while(~scanf("%d %d",&n,&m)){
46         memset(tree,0,sizeof(tree));
47         build(n);
48         while(m--){
49             scanf("%s %d %d",s,&a,&b);
50             if(s[0] == ‘Q‘) printf("%d\n",query(a,b));
51             else if(s[0] == ‘U‘) update(a,b);
52         }
53     }
54     return 0;
55 }