Package g2401_2500.s2415_reverse_odd_levels_of_binary_tree

Class Solution

java.lang.Object
g2401_2500.s2415_reverse_odd_levels_of_binary_tree.Solution
public class Solution extends java.lang.Object
2415 - Reverse Odd Levels of Binary Tree.

Medium

Given the root of a perfect binary tree, reverse the node values at each odd level of the tree.

  • For example, suppose the node values at level 3 are [2,1,3,4,7,11,29,18], then it should become [18,29,11,7,4,3,1,2].

Return the root of the reversed tree.

A binary tree is perfect if all parent nodes have two children and all leaves are on the same level.

The level of a node is the number of edges along the path between it and the root node.

Example 1:

Input: root = [2,3,5,8,13,21,34]

Output: [2,5,3,8,13,21,34]

Explanation:

The tree has only one odd level.

The nodes at level 1 are 3, 5 respectively, which are reversed and become 5, 3.

Example 2:

Input: root = [7,13,11]

Output: [7,11,13]

Explanation:

The nodes at level 1 are 13, 11, which are reversed and become 11, 13.

Example 3:

Input: root = [0,1,2,0,0,0,0,1,1,1,1,2,2,2,2]

Output: [0,2,1,0,0,0,0,2,2,2,2,1,1,1,1]

Explanation:

The odd levels have non-zero values.

The nodes at level 1 were 1, 2, and are 2, 1 after the reversal.

The nodes at level 3 were 1, 1, 1, 1, 2, 2, 2, 2, and are 2, 2, 2, 2, 1, 1, 1, 1 after the reversal.

Constraints:

  • The number of nodes in the tree is in the range [1, 214].
  • 0 <= Node.val <= 105
  • root is a perfect binary tree.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    TreeNode
    reverseOddLevels(TreeNode root)
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Solution

      public Solution()

  • Method Details