[LeetCode]Convert Sorted Array to Binary Search Tree

题目描述:(链接)

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

解题思路:

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        sortedArrayToBST(begin(nums), end(nums));
    }
private:
    TreeNode* sortedArrayToBST(vector<int>::iterator begin, vector<int>::iterator end) {
        auto len = distance(begin, end);
        if (len <= 0) return nullptr; 
        auto mid = begin + len / 2;
        TreeNode *root = new TreeNode(*mid);
        root->left = sortedArrayToBST(begin, mid);
        root->right = sortedArrayToBST(mid + 1, end);
    }
};