From a229253cdc7ff18d8d51bb9bc2ea8fcc384365b0 Mon Sep 17 00:00:00 2001
From: stupendousC <CarolineWuKaplan@gmail.com>
Date: Mon, 16 Sep 2019 08:44:24 -0700
Subject: [PATCH 1/2] lol i forgot to git push it

---
 lib/practice_exercises.rb | 86 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 80 insertions(+), 6 deletions(-)

diff --git a/lib/practice_exercises.rb b/lib/practice_exercises.rb
index 291e4e6..802f10e 100644
--- a/lib/practice_exercises.rb
+++ b/lib/practice_exercises.rb
@@ -1,13 +1,87 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n)
+# Space Complexity: O(n)
 def remove_duplicates(list)
-  raise NotImplementedError, "Not implemented yet"
+  # list is a sorted array of numbers
+  unique_list = []
+  
+  list.each do |element|
+    unless unique_list[-1] == element
+      unique_list << element
+    end
+  end
+  
+  return unique_list
 end
 
-# Time Complexity: ?
-# Space Complexity: ?
+
+
+
+# Time Complexity: O(n^2)
+# Space Complexity: O(n)
 def longest_prefix(strings)
-  raise NotImplementedError, "Not implemented yet"
+  shortest_string = strings.min_by { |string| string.length}  # O(n)
+  
+  match = ""
+  shortest_string.length.times do |index|   #O(n)
+    curr_char = strings[0][index]
+    
+    strings.each do |string|  #O(n)
+      if string[index] != curr_char
+        return match
+      end
+    end
+    
+    # all strings have matching letter on this index position
+    match << curr_char
+  end
+  
+  return match
+end
+
+
+
+
+
+def longest_prefix_ALT(strings)
+  # find the longest common prefix string amongst an array of strings
+  # Time O(n^2) and Space O(n)
+  
+  # get the match results from the first 2 strings 
+  prev_match = get_head_matches(strings[0], strings[1])
+  
+  # if the first 2 strings don't have any chars in common, answer is automatically ""
+  if prev_match == ""
+    return ""
+  end
+  
+  # compare the prev_match with each subsequent string, modifying prev_match with each iteration
+  ((strings.length)-2).times do |index|
+    prev_match = get_head_matches(prev_match, strings[index+2])
+    puts
+  end
+  
+  return prev_match
 end
 
+def get_head_matches(string1, string2)    
+  # O(n) time & O(1) space
+  shorter_string = [string1, string2].min_by { |str| str.length }
+  
+  index = 0
+  match = ""
+  
+  while index < shorter_string.length
+    if string1[index] == string2[index]
+      match << string1[index]
+    else 
+      break
+    end
+    
+    index += 1
+  end
+  
+  return match
+end
+
+

From 26a1d968e00b25563f1e17c77fd75c8b627b5234 Mon Sep 17 00:00:00 2001
From: stupendousC <CarolineWuKaplan@gmail.com>
Date: Mon, 16 Sep 2019 08:46:42 -0700
Subject: [PATCH 2/2] commented out unnecessary stuff

---
 lib/practice_exercises.rb | 80 ++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 39 deletions(-)

diff --git a/lib/practice_exercises.rb b/lib/practice_exercises.rb
index 802f10e..eda0483 100644
--- a/lib/practice_exercises.rb
+++ b/lib/practice_exercises.rb
@@ -43,45 +43,47 @@ def longest_prefix(strings)
 
 
 
-def longest_prefix_ALT(strings)
-  # find the longest common prefix string amongst an array of strings
-  # Time O(n^2) and Space O(n)
-  
-  # get the match results from the first 2 strings 
-  prev_match = get_head_matches(strings[0], strings[1])
-  
-  # if the first 2 strings don't have any chars in common, answer is automatically ""
-  if prev_match == ""
-    return ""
-  end
-  
-  # compare the prev_match with each subsequent string, modifying prev_match with each iteration
-  ((strings.length)-2).times do |index|
-    prev_match = get_head_matches(prev_match, strings[index+2])
-    puts
-  end
-  
-  return prev_match
-end
+#### ALTERNATE METHOD, THOUGHT I COULD DO BETTER THAN O(n^2) BUT COULDN'T ####
 
-def get_head_matches(string1, string2)    
-  # O(n) time & O(1) space
-  shorter_string = [string1, string2].min_by { |str| str.length }
-  
-  index = 0
-  match = ""
-  
-  while index < shorter_string.length
-    if string1[index] == string2[index]
-      match << string1[index]
-    else 
-      break
-    end
-    
-    index += 1
-  end
-  
-  return match
-end
+# def longest_prefix_ALT(strings)
+#   # find the longest common prefix string amongst an array of strings
+#   # Time O(n^2) and Space O(n)
+
+#   # get the match results from the first 2 strings 
+#   prev_match = get_head_matches(strings[0], strings[1])
+
+#   # if the first 2 strings don't have any chars in common, answer is automatically ""
+#   if prev_match == ""
+#     return ""
+#   end
+
+#   # compare the prev_match with each subsequent string, modifying prev_match with each iteration
+#   ((strings.length)-2).times do |index|
+#     prev_match = get_head_matches(prev_match, strings[index+2])
+#     puts
+#   end
+
+#   return prev_match
+# end
+
+# def get_head_matches(string1, string2)    
+#   # O(n) time & O(1) space
+#   shorter_string = [string1, string2].min_by { |str| str.length }
+
+#   index = 0
+#   match = ""
+
+#   while index < shorter_string.length
+#     if string1[index] == string2[index]
+#       match << string1[index]
+#     else 
+#       break
+#     end
+
+#     index += 1
+#   end
+
+#   return match
+# end