LC 0107 [E] Binary Tree Level Order Traversal II - ALawliet/algorithms GitHub Wiki

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def levelOrderBottom(self, root: TreeNode) -> List[List[int]]:
        res = deque()
        if root is None: return res
        Q = deque([root])
        while Q:
            levelSize = len(Q)
            currentLevel = []
            for _ in range(levelSize):
                currentNode = Q.popleft()
                currentLevel.append(currentNode.val)
                if currentNode.left:
                    Q.append(currentNode.left)
                if currentNode.right:
                    Q.append(currentNode.right)
            res.appendleft(currentLevel)
        return res