Problem Statement Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, from left to right, level by level from leaf to root). For example: Given binary tree {3,9,20,#,#,15,7},
|
1 2 3 4 5 |
3 / \ 9 20 / \ 15 7 |
return its bottom-up level order traversal as:
|
1 2 3 4 5 |
[ [15,7], [9,20], [3] ] |
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