All problems
MediumTrees

Binary Tree Right Side View

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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.

Examples

Example 1
    1
   / \
  2   3
   \   \
    5   4
Input
root = [1,2,3,null,5,null,4]
Output
[1,3,4]

At level 0, the rightmost node is 1. At level 1, the rightmost node is 3. At level 2, the rightmost node is 4.

Example 2
  1
   \
    3
Input
root = [1,null,3]
Output
[1,3]

At level 0, the rightmost node is 1. At level 1, the rightmost node is 3.

Example 3
Input
root = []
Output
[]

An empty tree has no visible nodes from any side.

Constraints

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

Optimal complexity

Time

O(n)

Space

O(n)

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