From d09a4d3eb080132e44b6ad79c16f7529d894bfcb Mon Sep 17 00:00:00 2001
From: Ivan Reshetnikov <ordinarydev@protonmail.com>
Date: Sat, 26 Nov 2022 11:27:25 +0500
Subject: [PATCH] Problem 14: longest common prefix

---
 problems/14-longest-common-prefix/main.rb | 26 +++++++++++++++++++++++
 problems/14-longest-common-prefix/test.rb | 18 ++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 problems/14-longest-common-prefix/main.rb
 create mode 100644 problems/14-longest-common-prefix/test.rb

diff --git a/problems/14-longest-common-prefix/main.rb b/problems/14-longest-common-prefix/main.rb
new file mode 100644
index 0000000..1aec2df
--- /dev/null
+++ b/problems/14-longest-common-prefix/main.rb
@@ -0,0 +1,26 @@
+# @param {String[]} strs
+# @return {String}
+def longest_common_prefix(strs)
+  # Find min length
+  min_length = strs[0].length
+  strs.each do |st|
+    if st.length < min_length
+      min_length = st.length
+    end
+  end
+  
+  res = ""
+  for i in 0..min_length - 1 do
+    strs.each do |st|
+      # If characters doesn't match
+      if st[i] != strs[0][i]
+        return res
+      end
+    end
+   
+    # All characters match
+    res += strs[0][i]
+  end
+
+  return res
+end
diff --git a/problems/14-longest-common-prefix/test.rb b/problems/14-longest-common-prefix/test.rb
new file mode 100644
index 0000000..7332c24
--- /dev/null
+++ b/problems/14-longest-common-prefix/test.rb
@@ -0,0 +1,18 @@
+require_relative "main"
+require "test/unit"
+ 
+class TestLCP < Test::Unit::TestCase
+ 
+  def test_simple
+    assert_equal("fl", longest_common_prefix(["flower","flow","flight"]) )
+  end
+
+  def test_empty_prefix
+    assert_equal("", longest_common_prefix(["dog","racecar","car"]) )
+  end
+
+  def test_empty_string
+    assert_equal("", longest_common_prefix([""]) )
+  end
+
+end