leetCode 108. Convert Sorted Array to Binary Search Tree JAVA

108. Convert Sorted Array to Binary Search Tree

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

   这到题把有序数组转成平衡二叉搜索树，所以选取数组的中点num[mid]作为根，对左右两边分别递归。

public TreeNode sortedArrayToBST(int[] nums) {
     int low=0;
     int high=nums.length-1;
     TreeNode root=sortedArrayToBST(nums, low, high);
     return root;
    }
    public TreeNode sortedArrayToBST(int[] nums,int low,int high){
    	TreeNode root=null;
    	if(low<=high){
    		int mid=(low+high)/2;
    		root=new TreeNode(nums[mid]);
    		root.left=sortedArrayToBST(nums, low, mid-1);
    		root.right=sortedArrayToBST(nums, mid+1, high);
    	}
    	return root;
    }