[LeetCode] 199 | Binary Tree Right Side View | Python

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문제 링크: https://leetcode.com/problems/binary-tree-right-side-view/

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문제

Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

 

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조건

• The number of nodes in the tree is in the range [0, 100].
• -100 <= Node.val <= 100

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내 풀이

right view이기 때문에 오른쪽 노드부터 확인해서 오른쪽 노드가 존재하면 ans에 추가한다.

왼쪽 노드는 같은 depth일 때의 오른쪽 노드가 없다면 ans에 추가한다.

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코드

# 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 rightSideView(self, root: Optional[TreeNode]) -> List[int]:
        if not root:    return []
        ans = [root.val]
        
        def recursive(root, depth):
            if root.right:
                if len(ans) <= depth:
                    ans.append(root.right.val)
                recursive(root.right, depth+1)
            
            if root.left:
                if len(ans) <= depth:
                    ans.append(root.left.val)
                
                recursive(root.left, depth+1)
            
        
        recursive(root, 1)
        return ans