leetcode/algorithms/ruby/0230-kth-smallest-element-in-a-bst.rb at main · remy727/leetcode · GitHub

Name: leetcode/algorithms/ruby/0230-kth-smallest-element-in-a-bst.rb at main · remy727/leetcode · GitHub
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# frozen_string_literal: true

# 230. Kth Smallest Element in a BST
# https://leetcode.com/problems/kth-smallest-element-in-a-bst
# Medium

=begin

Given the root of a binary search tree, and an integer k, return the kth smallest value (1-indexed) of all the values of the nodes in the tree.

### Example 1:
Input: root = [3,1,4,null,2], k = 1
Output: 1

### Example 2:
Input: root = [5,3,6,2,4,null,null,1], k = 3
Output: 3

### Constraints:
* The number of nodes in the tree is n.
* 1 <= k <= n <= 104
* 0 <= Node.val <= 104

=end

# Definition for a binary tree node.
# class TreeNode
# attr_accessor :val, :left, :right
# def initialize(val = 0, left = nil, right = nil)
# @val = val
# @left = left
# @right = right
# end
# end
# @param {TreeNode} root
# @param {Integer} k
# @return {Integer}
defkth_smallest(root,k)
find=->root{root && (find[root.left]or
(k -= 1) == 0 ? root.val :
find[root.right])}
find[root]
end