Package g2401_2500.s2415_reverse_odd_levels_of_binary_tree

Class Solution

  • public class Solution
extends 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 Detail

      • Solution

        public Solution()