hdu 1754 单点更新

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<cmath>
 6 #include<queue>
 7 using namespace std;
 8 int n,m,t;
 9 #define lson l,m,rt<<1
10 #define rson m+1,r,rt<<1|1
11 #define root 1,n,1
12 #define m ((l+r)>>1)
13 const int maxn=205555;
14 int cow[maxn];
15 int maxx[maxn<<2],minn[maxn<<2];
16 int mmax=-1,mmin=9999999;
17 void pushup(int rt){
18     maxx[rt]=max(maxx[rt<<1],maxx[rt<<1|1]);
19 }
20 void build(int l,int r,int rt){
21     if(l==r){
22         scanf("%d",&maxx[rt]);
23         return;
24     }
25     build(lson);
26     build(rson);
27     pushup(rt);
28 }
29 void query(int L,int R,int l,int r,int rt) {
30     if (L<=l&&r<=R){
31         mmax=max(mmax,maxx[rt]);
32         return;
33     }
34     int ret=0;
35     if(L<=m)  query(L,R,lson);
36     if(R>m)  query(L,R ,rson);
37 }
38 void update(int pos,int val,int l,int r,int rt)
39 {
40     if(l==r)    maxx[rt]=val;
41     else
42     {
43         if(pos<=m)  update(pos,val,lson);
44         else update(pos,val,rson);
45         pushup(rt);
46     }
47 }
48 int main()
49 {
50     int i,j,k;
51     #ifndef ONLINE_JUDGE
52     freopen("1.in","r",stdin);
53     #endif
54     int q;
55     while(scanf("%d%d",&n,&q)!=EOF)
56     {
57         build(root);
58         while(q--)
59         {
60             char s[10];
61             scanf("%s",s);
62             int a,b;
63             if(s[0]==‘Q‘)
64             {
65                 scanf("%d%d",&a,&b);
66                 mmax=-99999;
67                 query(a,b,root);
68                 printf("%d\n",mmax);
69             }
70             else
71             {
72                 scanf("%d%d",&a,&b);
73                 update(a,b,root);
74             }
75         }
76     }
77     return 0;
78 }