Class Solution


  • public class Solution
    extends Object
    107 - Binary Tree Level Order Traversal II.

    Medium

    Given the root of a binary tree, return the bottom-up level order traversal of its nodes’ values. (i.e., from left to right, level by level from leaf to root).

    Example 1:

    Input: root = [3,9,20,null,null,15,7]

    Output: [[15,7],[9,20],[3]]

    Example 2:

    Input: root = [1]

    Output: 1

    Example 3:

    Input: root = []

    Output: []

    Constraints:

    • The number of nodes in the tree is in the range [0, 2000].
    • -1000 <= Node.val <= 1000
    • Constructor Detail

      • Solution

        public Solution()