Merge pull request #785 from fartem/456_132_Pattern

2024-11-29 v. 7.1.3: added "456. 132 Pattern"

Author: fartem

README.md

@@ -579,3 +579,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 450. Delete Node in a BST                                       | [Link](https://leetcode.com/problems/delete-node-in-a-bst/)                                       | [Link](./lib/medium/450_delete_node_in_a_bst.rb)                                       | [Link](./test/medium/test_450_delete_node_in_a_bst.rb)                                       |
 | 451. Sort Characters By Frequency                               | [Link](https://leetcode.com/problems/sort-characters-by-frequency/)                               | [Link](./lib/medium/451_sort_characters_by_frequency.rb)                               | [Link](./test/medium/test_451_sort_characters_by_frequency.rb)                               |
 | 453. Minimum Moves to Equal Array Elements                      | [Link](https://leetcode.com/problems/minimum-moves-to-equal-array-elements/)                      | [Link](./lib/medium/453_minimum_moves_to_equal_array_elements.rb)                      | [Link](./test/medium/test_453_minimum_moves_to_equal_array_elements.rb)                      |
+| 456. 132 Pattern                                                | [Link](https://leetcode.com/problems/132-pattern/)                                                | [Link](./lib/medium/456_132_pattern.rb)                                                | [Link](./test/medium/test_456_132_pattern.rb)                                                |

leetcode-ruby.gemspec

@@ -5,7 +5,7 @@ require 'English'
 ::Gem::Specification.new do |s|
   s.required_ruby_version = '>= 3.0'
   s.name = 'leetcode-ruby'
-  s.version = '7.1.3'
+  s.version = '7.1.4'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/456_132_pattern.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/132-pattern/
+# @param {Integer[]} nums
+# @return {Boolean}
+def find132pattern(nums)
+  third = -::Float::INFINITY
+  stack = []
+  nums.reverse_each do |num|
+    return true if num < third
+
+    third = stack.pop while !stack.empty? && num > stack.last
+
+    stack << num
+  end
+
+  false
+end

test/medium/test_456_132_pattern.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/456_132_pattern'
+require 'minitest/autorun'
+
+class Pattern132Test < ::Minitest::Test
+  def test_default_one = assert(!find132pattern([1, 2, 3, 4]))
+
+  def test_default_two = assert(find132pattern([3, 1, 4, 2]))
+
+  def test_default_three = assert(find132pattern([-1, 3, 2, 0]))
+end