Package g0001_0100.s0099_recover_binary_search_tree

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    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].

    • <code>-2<sup>31</sup><= Node.val <= 2<sup>31</sup> - 1</code>

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

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Unit recoverTree(TreeNode root)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait