[리트코드] 104. Maximum Depth of Binary Tree

박형진·2022년 7월 19일
0

DFS 풀이

from collections import deque 

# 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 maxDepth(self, root: Optional[TreeNode]) -> int:
        if not root:
            return 0
        def dfs(node, depth):
            if not node:
                return depth - 1
            return max(dfs(node.left, depth + 1), dfs(node.right, depth + 1))
        return dfs(root, 1)

BFS 풀이

from collections import deque 

# 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 maxDepth(self, root: Optional[TreeNode]) -> int:
        if root is None:
            return 0;
        cnt = 0
        q = deque([root])
        
        while q:
            for i in range(len(q)):
                u = q.popleft()
                if u.left:
                    q.append(u.left)
                if u.right:
                    q.append(u.right)          
            cnt += 1
        return cnt
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