diff --git a/lib/practice_exercises.rb b/lib/practice_exercises.rb
index 291e4e6..1b670a4 100644
--- a/lib/practice_exercises.rb
+++ b/lib/practice_exercises.rb
@@ -1,13 +1,78 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n) n being all elements in the list. They are get iterated through
+#compared. 
+# Space Complexity: ?Would be O(1) the space stays the same throughout. No new arrays 
+# are created
+
+#compare the first number to all numbers until you reach a num thats not equal
+#Then replace taht first num with num that is different, and add to the counter
+#Once you reach the end of the array return the counter.
+
+
 def remove_duplicates(list)
-  raise NotImplementedError, "Not implemented yet"
+  if list.length == nil
+    return []
+  elsif list[0] == []
+    return []
+  end
+  
+  compare_to = list[0]
+  i = 0
+  counter = 0
+  
+  while list.length >= i
+    if compare_to == list[i]
+      list.delete_at(list[i])
+    elsif compare_to != list[i]
+      counter += 1
+      compare_to = list[i]
+    end
+    i += 1
+  end
+  return list
 end
 
-# Time Complexity: ?
-# Space Complexity: ?
+
+# Time Complexity: O(n^2)Each word gets iterated through and every letter in the word
+# gets iterated through. 
+# Space Complexity: No new Array is crated except common word. 
 def longest_prefix(strings)
-  raise NotImplementedError, "Not implemented yet"
+
+  common_word = ""
+  strings.each_with_index do |word, index|
+    if strings[0][index] == word[index]
+      common_word += word[index]
+    else
+      return common_word
+    end
+  end
+ return common_word
 end
 
+
+# i = 0
+# common_word = ""
+# #while array[0].length >= 0
+# array.each_with_index do |word, index|
+#   if array[0][i] == word[i]
+#     common_word += array[0][i]
+#     i +=1
+#   else
+#     puts common_word
+#   end
+# end
+# puts "here #{common_word}"
+
+
+
+# i = 1
+# counter = 1
+# compare = strings[0]
+# while strings.length >= i 
+#   if compare[0..counter] != strings[i][0..counter]
+#     return ""
+#   else
+#     i += 1
+#   end
+# end
+# return compare[0..1]
\ No newline at end of file
diff --git a/test/practice_exercises_test.rb b/test/practice_exercises_test.rb
index 4d0bc10..9de4109 100644
--- a/test/practice_exercises_test.rb
+++ b/test/practice_exercises_test.rb
@@ -1,5 +1,6 @@
 require_relative "test_helper"
 
+
 describe "Practice Exercises" do
   describe "remove duplicates" do
     it "works for 1 element strings" do