From 5153895a6691c3ba599d5bac16e4dbf04cc2c54a Mon Sep 17 00:00:00 2001
From: fartem <jaman.smlnsk@gmail.com>
Date: Thu, 31 Oct 2024 08:39:42 +0300
Subject: [PATCH] 2024-10-31 v. 6.9.3: added "378. Kth Smallest Element in a
 Sorted Matrix"

---
 README.md                                     |  1 +
 leetcode-ruby.gemspec                         |  2 +-
 ...kth_smallest_element_in_a_sorted_matrix.rb | 34 +++++++++++++++++++
 ...kth_smallest_element_in_a_sorted_matrix.rb | 31 +++++++++++++++++
 4 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 lib/medium/378_kth_smallest_element_in_a_sorted_matrix.rb
 create mode 100644 test/medium/test_378_kth_smallest_element_in_a_sorted_matrix.rb

diff --git a/README.md b/README.md
index 0d2ac392..e1d3a7fe 100644
--- a/README.md
+++ b/README.md
@@ -558,3 +558,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 347. Top K Frequent Elements                                    | [Link](https://leetcode.com/problems/top-k-frequent-elements/)                                    | [Link](./lib/medium/347_top_k_frequent_elements.rb)                                    | [Link](./test/medium/test_347_top_k_frequent_elements.rb)                                    |
 | 371. Sum of Two Integers                                        | [Link](https://leetcode.com/problems/sum-of-two-integers/)                                        | [Link](./lib/medium/371_sum_of_two_integers.rb)                                        | [Link](./test/medium/test_371_sum_of_two_integers.rb)                                        |
 | 377. Combination Sum IV                                         | [Link](https://leetcode.com/problems/combination-sum-iv/)                                         | [Link](./lib/medium/377_combination_sum_iv.rb)                                         | [Link](./test/medium/test_377_combination_sum_iv.rb)                                         |
+| 378. Kth Smallest Element in a Sorted Matrix                    | [Link](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/)                    | [Link](./lib/medium/378_kth_smallest_element_in_a_sorted_matrix.rb)                    | [Link](./test/medium/test_378_kth_smallest_element_in_a_sorted_matrix.rb)                    |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 802e889d..d6eb05ea 100644
--- a/leetcode-ruby.gemspec
+++ b/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 = '6.9.2'
+  s.version = '6.9.3'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/378_kth_smallest_element_in_a_sorted_matrix.rb b/lib/medium/378_kth_smallest_element_in_a_sorted_matrix.rb
new file mode 100644
index 00000000..eb277d64
--- /dev/null
+++ b/lib/medium/378_kth_smallest_element_in_a_sorted_matrix.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/
+# @param {Integer[][]} matrix
+# @param {Integer} k
+# @return {Integer}
+def kth_smallest378(matrix, k)
+  n = matrix.length
+  l = matrix[0][0]
+  h = matrix[n - 1][n - 1]
+  m = 0
+  temp = 0
+  count = 0
+
+  while l < h
+    m = l + (h - l) / 2
+    temp = n - 1
+    count = 0
+
+    matrix.each do |mat|
+      temp -= 1 while temp >= 0 && mat[temp] > m
+
+      count += (temp + 1)
+    end
+
+    if count < k
+      l = m + 1
+    else
+      h = m
+    end
+  end
+
+  l
+end
diff --git a/test/medium/test_378_kth_smallest_element_in_a_sorted_matrix.rb b/test/medium/test_378_kth_smallest_element_in_a_sorted_matrix.rb
new file mode 100644
index 00000000..0c3a6957
--- /dev/null
+++ b/test/medium/test_378_kth_smallest_element_in_a_sorted_matrix.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/378_kth_smallest_element_in_a_sorted_matrix'
+require 'minitest/autorun'
+
+class KthSmallestElementInASortedMatrixTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      13,
+      kth_smallest378(
+        [
+          [1, 5, 9],
+          [10, 11, 13],
+          [12, 13, 15]
+        ],
+        8
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      -5,
+      kth_smallest378(
+        [[-5]],
+        1
+      )
+    )
+  end
+end