392. Is Subsequence

Author: remy727

README.md

@@ -48,6 +48,7 @@
 | 344 | Reverse String | [Ruby](./algorithms/ruby/0344-reverse-string.rb) | Easy |
 | 382 | Linked List Random Node | [Ruby](./algorithms/ruby/0382-linked-list-random-node.rb) | Medium |
 | 387 | First Unique Character in a String | [Ruby](./algorithms/ruby/0387-first-unique-character-in-a-string.rb) | Easy |
+| 392 | Is Subsequence | [Ruby](./algorithms/ruby/0392-is-subsequence.rb) | Easy |
 | 427 | Construct Quad Tree | [Ruby](./algorithms/ruby/0427-construct-quad-tree.rb) | Medium |
 | 438 | Find All Anagrams in a String | [Ruby](./algorithms/ruby/0438-find-all-anagrams-in-a-string.rb) | Medium |
 | 443 | String Compression | [Ruby](./algorithms/ruby/0443-string-compression.rb) [Python3](./algorithms/python3/0443-string-compression.py) | Medium |

algorithms/ruby/0392-is-subsequence.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+# 392. Is Subsequence
+# https://leetcode.com/problems/is-subsequence
+
+=begin
+
+Given two strings s and t, return true if s is a subsequence of t, or false otherwise.
+
+A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., "ace" is a subsequence of "abcde" while "aec" is not).
+
+### Example 1:
+
+Input: s = "abc", t = "ahbgdc"
+Output: true
+
+### Example 2:
+
+Input: s = "axc", t = "ahbgdc"
+Output: false
+
+### Constraints:
+
+* 0 <= s.length <= 100
+* 0 <= t.length <= 104
+* s and t consist only of lowercase English letters.
+
+=end
+
+# @param {String} s
+# @param {String} t
+# @return {Boolean}
+def is_subsequence(s, t)
+  return true if s.size == 0
+  return false if s.size > t.size
+
+  sp = 0
+  t.chars.each do |char|
+    if s[sp] == char
+      sp += 1
+      return true if sp == s.size
+    end
+  end
+
+  false
+end
+
+# **************** #
+#       TEST       #
+# **************** #
+
+require "test/unit"
+class Test_is_subsequence < Test::Unit::TestCase
+  def test_
+    assert_equal true, is_subsequence("abc", "ahbgdc")
+    assert_equal false, is_subsequence("axc", "ahbgdc")
+  end
+end