1 #include<bits/stdc++.h> 2 using namespace std; 3 typedef long long ll; 4 struct node{ 5     int left,right,max; 6 }tree[800002]; 7 int num[200002]; 8 char ch; 9 int t1,t2;10 int build(int root,int left,int right){11     tree[root].left=left;12     tree[root].right=right;13     if(left==right) return tree[root].max=num[left];14     15     int a,b,mid;16     mid=(left+right)/2;17     a=build(2*root,left,mid);18     b=build(2*root+1,mid+1,right);19     return tree[root].max=max(a,b);20 }21 22 int find(int root,int left,int right){23     if(right<tree[root].left||left>tree[root].right) return 0;24     if(left<=tree[root].left&&tree[root].right<=right) return tree[root].max;25     26     int a,b;27     a=find(2*root,left,right);28     b=find(2*root+1,left,right);29     return max(a,b);//find时不能赋值 30 }31 32 int update(int root,int pos,int val){33     if(pos<tree[root].left||pos>tree[root].right) return tree[root].max;34     if(pos==tree[root].left&&pos==tree[root].right) return tree[root].max=val;35     36     int a,b;37     a=update(2*root,pos,val);38     b=update(2*root+1,pos,val);39     return tree[root].max=max(a,b);40 }41 int n,m;42 int main(){43     while(scanf("%d%d",&n,&m)!=EOF){44         memset(num,0,sizeof num);45         memset(tree,0,sizeof tree);46         for(int i=1;i<=n;i++){47             scanf("%d",num+i);48         }49         build(1,1,n);50         for(int i=0;i<m;i++){51             getchar();52             scanf("%c%d%d",&ch,&t1,&t2);53             if(ch==‘Q‘){54                 int res=find(1,t1,t2);55                 printf("%d\n",res);56             }57             else{58                 update(1,t1,t2);59             }60         }61     }62     63 }