Merge pull request #661 from fartem/19_Remove_Nth_Node_From_End_of_List

2024-07-04 v. 6.0.4: added "19. Remove Nth Node From End of List"

Author: fartem

README.md

@@ -469,3 +469,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 15. 3Sum                                          | [Link](https://leetcode.com/problems/3sum/)                                           | [Link](./lib/medium/15_3sum.rb)                                          |
 | 16. 3Sum Closest                                  | [Link](https://leetcode.com/problems/3sum-closest/)                                   | [Link](./lib/medium/16_3sum_closest.rb)                                  |
 | 17. Letter Combinations of a Phone Number         | [Link](https://leetcode.com/problems/letter-combinations-of-a-phone-number/)          | [Link](./lib/medium/17_letter_combinations_of_a_phone_number.rb)         |
+| 19. Remove Nth Node From End of List              | [Link](https://leetcode.com/problems/remove-nth-node-from-end-of-list/)               | [Link](./lib/medium/19_remove_nth_node_from_end_of_list.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 = '6.0.3'
+  s.version = '6.0.4'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[bin/leetcode-ruby README.md LICENSE]
   s.executable = 'leetcode-ruby'

lib/medium/19_remove_nth_node_from_end_of_list.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/remove-nth-node-from-end-of-list/
+# @param {ListNode} head
+# @param {Integer} n
+# @return {ListNode}
+def remove_nth_from_end(head, n)
+  nodes = []
+  curr = head
+
+  until curr.nil?
+    nodes << curr
+    curr = curr.next
+  end
+
+  index = nodes.length - n
+  prev = index.zero? ? nil : nodes[index - 1]
+  nxt = index == nodes.length - 1 ? nil : nodes[index + 1]
+
+  if prev.nil?
+    head = nxt
+  else
+    prev.next = nxt
+  end
+
+  head
+end

test/medium/test_19_remove_nth_node_from_end_of_list.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/19_remove_nth_node_from_end_of_list'
+require_relative '../../lib/common/linked_list'
+require 'minitest/autorun'
+
+class RemoveNthNodeFromEndOfListTest < ::Minitest::Test
+  def test_default
+    assert(
+      ::ListNode.are_equals(
+        ::ListNode.from_array(
+          [1, 2, 3, 5]
+        ),
+        remove_nth_from_end(
+          ::ListNode.from_array(
+            [1, 2, 3, 4, 5]
+          ),
+          2
+        )
+      )
+    )
+    assert(
+      ::ListNode.are_equals(
+        ::ListNode.from_array([]),
+        remove_nth_from_end(
+          ::ListNode.from_array([1]),
+          1
+        )
+      )
+    )
+    assert(
+      ::ListNode.are_equals(
+        ::ListNode.from_array([1]),
+        remove_nth_from_end(
+          ::ListNode.from_array([1, 2]),
+          1
+        )
+      )
+    )
+  end
+end