LeetCode --- Convert Sorted Array to Binary Search Tree
Problem discription:
Given an array where elements are sorted in ascending order, convert it to a height balanced BST.
Accepted Code:
1 /**
2 * Definition for binary tree
3 * struct TreeNode {
4 * int val;
5 * TreeNode *left;
6 * TreeNode *right;
7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {}
8 * };
9 */
10 class Solution {
11 public:
12 TreeNode *sortedArrayToBST(vector<int> &num, int start, int end) {
13 if (start > end) {
14 return NULL;
15 }
16 // if you write " int middle = start + (end - start) >> 1"
17 // instead of the following sentence, you should keep in
18 // mind that the priority of ">>" is weaker than "+" operator
19 int middle = start + (end - start) / 2;
20 TreeNode *p = new TreeNode(num[middle]);
21 // elements at the left of num[middle] construct
22 // the left child tree of "p" and its right child
23 // tree consists of elements located at the right
24 // of num[middle]...
25 // because the given array is sorted
26 if (start != end) {
27 p->left = sortedArrayToBST(num, start, middle - 1);
28 p->right = sortedArrayToBST(num, middle + 1, end);
29 }
30 return p;
31 }
32 TreeNode *sortedArrayToBST(vector<int> &num) {
33 // call the overload function
34 return sortedArrayToBST(num, 0, num.size() - 1);
35 }
36 };
posted on 2014-06-14 17:54 Stomach_ache 阅读(132) 评论(0) 编辑 收藏 举报
