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199. Binary Tree Right Side View

Tree Depth-First Search Breadth-First Search Binary Tree

Problem - Binary Tree Right Side View

Medium

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.

 

Example 1:

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

Output: [1,3,4]

Explanation:

Example 2:

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

Output: [1,3,4,5]

Explanation:

Example 3:

Input: root = [1,null,3]

Output: [1,3]

Example 4:

Input: root = []

Output: []

 

Constraints:

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

Solutions

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# 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]:
        result = []

        def dfs(root, depth: int):
            if root is None:
                return
            if len(result) == depth:
                result.append(root.val)

            dfs(root.right, depth + 1)
            dfs(root.left, depth + 1)

        dfs(root, 0)
        return result

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 17.7 MB (60.73%)