#include<bits/stdc++.h>
using namespace std;
const int maxn=1005;

void build_tree(int arr[],int tree[],int node,int start,int end)
{
    if(start==end){
        tree[node]=arr[start];
    }
    else{
        int left_node  = 2*node+1;
        int right_node = 2*node+2;
        int mid=(start+end)/2;
        build_tree(arr,tree,left_node,start,mid);
        build_tree(arr,tree,right_node,mid+1,end);
        tree[node]=tree[left_node]+tree[right_node];
    }
}
void upate_tree(int arr[],int tree[],int node,int start,int end,int idx,int val)
{
    if(start==end)
    {
        //tree[node]=arr[start];
        arr[idx]=val;
        tree[node]=val;
    }
    else
    {
        int left_node  = 2*node+1;
        int right_node = 2*node+2;
        int mid=(start+end)/2;
        if(start<=idx && idx<=mid)
        {
            upate_tree(arr,tree,left_node,start,mid,idx,val);
        }
        else
        {
            upate_tree(arr,tree,right_node,mid+1,end,idx,val);
        }
        tree[node]=tree[left_node]+tree[right_node];
    }
}

int query_tree(int arr[],int tree[],int node,int start,int end,int L,int R)
{
    //打印递归过程
    cout<<"start="<<start<<","<<"end="<<end<<'\n';
    //求区间[L,R]之间的和
    if(R<start || L>end)
    {
        return 0;
    }
     else if(L<=start && end<=R){
        return tree[node];
    }
    else if(start==end)
    {
        return tree[node];
    }
    else{
        int mid=(start+end)/2;
        int left_node=2*node+1;
        int right_node=2*node+2;
        int sum_left=query_tree(arr,tree,left_node,start,mid,L,R);
        int sum_right=query_tree(arr,tree,right_node,mid+1,end,L,R);
        return sum_left+sum_right;
    }
}
int main()
{    int a[6]= {1,3,5,7,9,11};
    int size=6;
    int tree[maxn]= {0};
    build_tree(a,tree,0,0,size-1);
    for(int i=0; i<15; i++)
    {
        cout<<"tree["<<i<<"]="<<tree[i]<<'\n';
    }
    cout<<'\n';

    upate_tree(a,tree,0,0,size-1,4,6);//将a[4]的值更新为6
//    for(int i=0; i<15; i++)
//    {
//        cout<<"tree["<<i<<"]="<<tree[i]<<'\n';
//    }
  int s=query_tree(a,tree,0,0,size-1,2,5);//查询区间[2，5]的和
   cout<<s<<'\n';
    return 0;
}