LeetCode-108. 将有序数组转换为二叉搜索树

LeetCode108. 将有序数组转换为二叉搜索树

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public TreeNode sortedArrayToBST(int[] nums) {
        return nums==null?null:buildTree(nums,0,nums.length-1);
    }
    public TreeNode buildTree(int[] nums,int l,int r){
        if(l>r){
            return null;
        }
        int m = l + (r-l)/2;
        TreeNode root = new TreeNode(nums[m]);
        root.left = buildTree(nums,l,m-1);
        root.right = buildTree(nums,m+1,r);
        return root;
    }

}