Class Solution


  • public class Solution
    extends Object
    99 - Recover Binary Search Tree.

    Medium

    You are given the root of a binary search tree (BST), where the values of exactly two nodes of the tree were swapped by mistake. Recover the tree without changing its structure.

    Example 1:

    Input: root = [1,3,null,null,2]

    Output: [3,1,null,null,2]

    Explanation: 3 cannot be a left child of 1 because 3 > 1. Swapping 1 and 3 makes the BST valid.

    Example 2:

    Input: root = [3,1,4,null,null,2]

    Output: [2,1,4,null,null,3]

    Explanation: 2 cannot be in the right subtree of 3 because 2 < 3. Swapping 2 and 3 makes the BST valid.

    Constraints:

    • The number of nodes in the tree is in the range [2, 1000].
    • -231 <= Node.val <= 231 - 1

    Follow up: A solution using O(n) space is pretty straight-forward. Could you devise a constant O(1) space solution?

    • Constructor Detail

      • Solution

        public Solution()
    • Method Detail

      • recoverTree

        public void recoverTree​(TreeNode root)