#958

Check Completeness of a Binary Tree

specialist · 720 · lc medium +30 · verified · 59% accepted · 4,532 likes · top 56%

Description

A complete binary tree has all levels entirely filled except possibly the deepest, where nodes are packed as far left as possible. Given the root of a binary tree, return true if the tree is complete, false otherwise.

Example 1:

Input: root = [1,2,3,4,5,6]

Output: true

Explanation: Every level before the last is full (ie. levels with node-values {1} and {2, 3}), and all nodes in the last level ({4, 5, 6}) are as far left as possible.

Example 2:

Input: root = [1,2,3,4,5,null,7]

Output: false

Explanation: The node with value 7 isn't as far left as possible.

Code

# 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 isCompleteTree(self, root: Optional[TreeNode]) -> bool:

# 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 isCompleteTree(self, root: Optional[TreeNode]) -> bool: