LeetCode in TypeScript
199. 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]
Example 2:
Input: root = [1,null,3]
Output: [1,3]
Example 3:
Input: root = []
Output: []
Constraints:
- The number of nodes in the tree is in the range
[0, 100]. -100 <= Node.val <= 100
Solution
import { TreeNode } from '../../com_github_leetcode/treenode'
/**
* Definition for a binary tree node.
* class TreeNode {
* val: number
* left: TreeNode | null
* right: TreeNode | null
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
* }
*/
function rightSideView(root: TreeNode | null): number[] {
const result: number[] = []
function recurse(node: TreeNode | null, level: number): void {
if (node !== null) {
if (result.length === level) {
result.push(node.val)
}
recurse(node.right, level + 1)
recurse(node.left, level + 1)
}
}
recurse(root, 0)
return result
}
export { rightSideView }