[leetcode]Convert Sorted Array to Binary Search Tree

Convert Sorted Array to Binary Search Tree

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

算法：根据有序数组，生成BST，递归实现。

代码如下：

public class Solution {
    public TreeNode sortedArrayToBST(int[] num) {
          if(num == null || num.length == 0) return null;
          int mid = num.length >> 1;
          TreeNode node = new TreeNode(num[mid]);
          int[] left = Arrays.copyOfRange(num, 0, mid);
          int[] right = Arrays.copyOfRange(num, mid + 1, num.length);
          node.left = sortedArrayToBST(left);
          node.right = sortedArrayToBST(right);
          return node;
     
    }
}