HDU 1754 I Hate It (线段树)

简单的线段树，多余的就不解释了。
 1 #include<cstdio>
 2 #include<iostream>
 3 
 4 using namespace std;
 5 #define INF 0xffffff0
 6 #define max(a,b) (a>b?a:b)
 7 #define min(a,b) (a<b?a:b)
 8 struct Node
 9 {
10     int maxV;
11     int L, R;
12     int Mid()
13     {
14         return (L+R)/2;
15     }
16 }Tree[800010];
17 int maxV = 0;
18 void BuildTree(int root,int L,int R);
19 void Query(int root,int s,int e);
20 void Insert(int root,int i,int v);//第i个数 为 V
21 
22 int main()
23 {
24     int N, M;
25     while(scanf("%d%d",&N,&M) != EOF)
26     {
27         int k;
28         BuildTree(0,1,N);
29         for(int i = 1; i <= N; i++)
30         {
31             scanf("%d",&k);
32             Insert(0,i,k);
33         }
34         while(M--)
35         {
36             int s, e;
37             char str[2];
38             maxV = 0;
39             scanf("%s%d%d",str,&s,&e);
40             if(str[0] == 'Q')
41             {
42                 Query(0,s,e);
43                 printf("%d
",maxV);
44             }
45             else
46                 Insert(0,s,e);
47         }
48     }
49     return 0;
50 }
51 
52 void BuildTree(int root,int L,int R)
53 {
54     Tree[root].L = L;
55     Tree[root].R = R;
56     Tree[root].maxV = 0;
57     if(L != R)
58     {
59         BuildTree(root*2+1,L,Tree[root].Mid());
60         BuildTree(root*2+2,Tree[root].Mid()+1,R);
61     }
62 }
63 void Query(int root,int s,int e)
64 {
65     if(Tree[root].maxV <= maxV)
66         return ;
67     if(Tree[root].L == s && Tree[root].R == e)
68     {
69         maxV = max(Tree[root].maxV, maxV);
70         return ;
71     }
72     if(e <= Tree[root].Mid())
73         Query(root*2+1,s, e);
74     else if( s > Tree[root].Mid())
75         Query(root*2+2,s, e);
76     else
77     {
78         Query(root*2+1,s,Tree[root].Mid());
79         Query(root*2+2,Tree[root].Mid()+1,e);
80     }
81 }
82 void Insert(int root,int i,int v)//第i个数 为 V
83 {
84     if(Tree[root].L == Tree[root].R)
85     {
86         Tree[root].maxV = v;
87         return ;
88     }
89     Tree[root].maxV = max(v,Tree[root].maxV);
90     if(i <= Tree[root].Mid())
91         Insert(root*2+1,i,v);
92     else
93         Insert(root*2+2,i,v);
94 }