[Leetcode] Range Sum query-mutable

This problem requires a new data structure---Segment Tree. Geeksforgeeks article to get some ideas of it. However, the code in this article is too verbose. To solve this problem using segment tree, 2guotou have posted a very nice Java code, which are rewritten below in C + +. I try to conform to the leetcode traditions of defining structures and classes.

1 structSegmenttreenode {2     ints, e, sum;3segmenttreenode*Left ;4segmenttreenode*Right ;5Segmenttreenode (int_s,int_e): S (_s), E (_e), SUM (0), left (null), right (null) {}6 };7 8 classSegmenttree {9  Public:TenSegmenttree (vector<int>&nums) { One         intn =nums.size (); ARoot = Buildst (Nums,0N1); -     } -  the     voidUpdateintIintval) { - Update (root, I, Val); -     } -  +     intSumrange (intIintj) { -         returnSumrange (Root, I, j); +     } A Private: atsegmenttreenode*Root; -segmenttreenode* BUILDST (vector<int>& Nums,intSinte) { -         if(S > E)returnNULL; -         Else { -segmenttreenode* res =NewSegmenttreenode (S, e); -             if(s = = e) Res->sum =Nums[s]; in             Else { -                 intm = s + (e-s)/2; toRes->left =BUILDST (Nums, S, m); +Res->right = Buildst (nums, M +1, e); -Res->sum = Res->left->sum + res->right->sum; the             } *             returnRes; $         }Panax Notoginseng     } -     voidUpdate (segmenttreenode* root,intIintval) { the         if(Root->s = = root->e) Root->sum =Val; +         Else { A             intm = root->s + (root->e-root->s)/2; the             if(i <= m) update (root->Left , I, Val); +             ElseUpdate (root->Right , I, Val); -Root->sum = Root->left->sum + root->right->sum; $         } $     } -     intSumrange (segmenttreenode* root,intSinte) { -         if(Root->s = = S && root->e = = e)returnRoot->sum; the         Else { -             intm = root->s + (root->e-root->s)/2;Wuyi             if(e <= m)returnSumrange (root->Left , S, e); the             Else if(s >= m +1)returnSumrange (root->Right , S, e); -             Else returnSumrange (Root->left, S, m) + Sumrange (root->right, M +1, e); Wu         } -     } About }; $  - classNumarray { -  Public: -Numarray (vector<int>&nums) { ASt =NewSegmenttree (nums); +     } the  -     voidUpdateintIintval) { $St->update (I, Val); the     } the  the     intSumrange (intIintj) { the         returnSt->Sumrange (i, j); -     } in Private: thesegmenttree*St; the }; About  the  the //Your Numarray object would be instantiated and called as such: the //Numarray Numarray (nums); + //numarray.sumrange (0, 1); - //numarray.update (1, ten); the //Numarray.sumrange (1, 2);

[Leetcode] Range Sum query-mutable