LeetCode/java/convert-sorted-array-to-binary-search-tree.java

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    private TreeNode sortedArrayToBST(int[] nums, int min, int max) {
        if (min > max) {
            return null;
        }

        int mid = (min + max) / 2;
        return new TreeNode(
            nums[mid],
            sortedArrayToBST(nums, min, mid - 1),
            sortedArrayToBST(nums, mid + 1, max)
        );
    }

    public TreeNode sortedArrayToBST(int[] nums) {
        return sortedArrayToBST(nums, 0, nums.length - 1);
    }
}