[LeetCode] 104. Maximum Depth of Binary Tree

- Problem

104. Maximum Depth of Binary Tree

- 내 풀이 1 (dfs, iteration)

class Solution:
    def maxDepth(self, root: Optional[TreeNode]) -> int:
        if not root:
            return 0

        stk = [(root, 1)]
        answer = 1

        while stk:
            root, depth = stk.pop()
            answer = max(answer, depth)

            if root.left:
                stk.append((root.left, depth + 1))
            
            if root.right:
                stk.append((root.right, depth + 1))
        
        return answer

- 결과

- 내 풀이 2 (dfs, recursion)

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

디음 코드와 같이 중첩 함수를 사용하지 않는 방법도 있다.

class Solution:
    def maxDepth(self, root: Optional[TreeNode]) -> int:
        if not root:
            return 0
        
        left_depth = self.maxDepth(root.left)
        right_depth = self.maxDepth(root.right)
        
        return max(left_depth, right_depth) + 1

- 결과