HDU 1754 - I Hate It

裸的线段树求区间的最大值。

 1 #include <cstdio>
 2 #include <iostream>
 3 using namespace std;
 4 
 5 #define MAXN    262144
 6 
 7 int _v[MAXN << 1];
 8 int *v = &_v[-1];
 9 
10 #define lsp p<<1
11 #define rsp lsp | 1
12 #define pushup(p)    (v[p] = max(v[lsp],v[rsp]))
13 #define lso    l,m,lsp
14 #define rso    m+1,r,rsp
15 
16 #define recusive_def    int l, int r, int p
17 
18 void build(recusive_def)
19 {
20     if (l == r) scanf("%d", &v[p]);
21     else {
22         int m = l+r >> 1;
23         build(lso), build(rso);
24         pushup(p);
25     }
26 }
27 
28 void update(int o, int oval, recusive_def)
29 {
30     if (l == r) v[p] = oval;
31     else {
32         int m = l+r >> 1;
33         if (o <= m) update(o, oval, lso);
34         else update(o, oval, rso);
35         pushup(p);
36     }
37 }
38 
39 int query(int L, int R, recusive_def)
40 {
41     if (L<=l && r<=R) return v[p];
42     else {
43         int m = l+r >> 1;
44         return max(L <= m? query(L, R, lso) : 0, R > m ? query(L, R, rso): 0);
45     }
46 }
47 
48 int main(void)
49 {
50 //    freopen("hdu1754.txt", "r", stdin);
51     int N, Q;
52     while(scanf("%d%d", &N, &Q) > 0){
53         build(1, N, 1);
54 
55         for(; Q; --Q) {
56             char op;
57             int L, R;
58             scanf("\n%c%d%d", &op, &L, &R);
59             if (op == 'Q') printf("%d\n", query(L,R, 1, N, 1));
60             else update(L, R, 1, N, 1);
61         }
62     }
63     return 0;
64 }

 

2014-06-03 21:21:37 Accepted 1754 1109MS 2348K 1149 B G++
posted @ 2014-06-03 21:42  e0e1e  阅读(177)  评论(0)  编辑  收藏  举报