Grokking Data Structures & Algorithms for Coding Interviews
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Solution: Binary Tree Right Side View

Problem Statement

Return the values of the nodes visible from the right of a binary tree, top down. A node is visible when it is the rightmost node on its level.

Examples

Example 1

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

Example 2

  • Input: root = [1, null, 3]
  • Expected Output: [1, 3]

Example 3

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

Reading the question properly

The word right in the title is misleading, and the third example is there to prove it

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Sajid Khan

Sajid Khan

· 3 days ago

// I was able to solve it using preorder traversal, but I swapped the traversal order of the left and right subtrees

class Solution {
  rightSideView(root) {
    const result = [];

    this.preOrderTraverse(root, result, 0)
    return result;
  }

  preOrderTraverse(root, result, index) {
    if (root === null) return;

    if (result.length === index) result.push(root.val);

    this.preOrderTraverse(root.right, result, index + 1)
    this.preOrderTraverse(root.left, result, index + 1)
  }
}
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