hdu 1754 线段树模板题

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1754

 #include <cstdio>
 #include <cmath>
 #include <algorithm>
 #include <iostream>
 #include <cstring>
 #include <queue>
 #include <vector>

 #define maxn 230050
 #define lson l,mid,u<<1
 #define rson mid+1,r,u<<1|1
 using namespace std;

 const int INF = 0x3f3f3f;

 int seg[maxn<<];

 int Push_UP(int u){
     seg[u] = max(seg[u<<],seg[u<<|]);  //****这个地方 u<<1|1 不能换为 u << 1 +1
 }
 void build(int l,int r,int u){
     if(l == r){
         scanf("%d",&seg[u]);
         return;
     }
     int mid = (l + r)/;
     build(lson);
     build(rson);
     Push_UP(u);
 }
 void Update(int loc,int num,int l,int r,int u){
     if(l == r){  // 这个地方要注意！！
         seg[u] = num;
         return;
     }
     int mid = (l + r)/;
     if(loc <= mid) Update(loc,num,lson);
     else           Update(loc,num,rson);
     Push_UP(u);
 }
 int Query(int L,int R,int l,int r,int u){
     if(L <= l && r <= R){
         return seg[u];
     }
     int ret = ;
     int mid = (l + r)/;
     if(L <= mid)    ret =max(ret,Query(L,R,lson));
     if(R >  mid)    ret =max(ret,Query(L,R,rson));
     return ret;
 }
 int main()
 {
     if(freopen("input.txt","r",stdin)== NULL)  {printf("Error\n"); exit();}
     int N,M;
     while(cin>>N>>M){
         build(,N,);
         while(M--){
             char query[];
             int l,r;
             scanf("%s%d%d",query,&l,&r);
             if(query[] == 'U')  Update(l,r,,N,);
             else{
                 int ans = Query(l,r,,N,);
                 printf("%d\n",ans);
             }
         }
     }
 }