diff --git a/lib/practice_exercises.rb b/lib/practice_exercises.rb
index 291e4e6..1f5c3a3 100644
--- a/lib/practice_exercises.rb
+++ b/lib/practice_exercises.rb
@@ -1,13 +1,68 @@
-
-# Time Complexity: ?
-# Space Complexity: ?
+require 'pry'
+# Time Complexity: O(n) - as array size grows, the evaluation grows at the same rate 
+# Space Complexity: O(1) - no new data structures are being made
 def remove_duplicates(list)
-  raise NotImplementedError, "Not implemented yet"
+  if list.length == 1
+    return list
+  end
+  
+  i = 0
+  
+  list.each do |number|
+    if number[i+1] == number[i]
+      list.delete_at(i)
+    else 
+      i += 1
+    end
+  end
+  
+  return list
+  
 end
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n) - Although there are several loops, they are both proportional to the array being tested
+# Space Complexity: O(1) - no new data structures are being made
+
+# strings being passed in is an array of strings
 def longest_prefix(strings)
-  raise NotImplementedError, "Not implemented yet"
+  
+  max_length = strings[0].length
+  
+  return_statement = nil
+  
+  strings.each do |string|
+    if string.length > 0 && string.length < max_length
+      max_length = string.length
+    elsif string.length == 0
+      return_statement = ""
+    end
+  end
+  
+  if return_statement != nil
+    return return_statement
+  end
+  
+  i = 0 # I am the word you're on
+  j = 0 # I am the character you're on
+  k = 0 # I am the last characer that matched
+  
+  # binding.pry
+  until j == max_length || i + 1 == strings.length do
+    if strings[i][j] == strings[i + 1][j]
+      i += 1
+      j += 1
+      k = j
+    else 
+      k -= 1
+      break
+    end
+    
+  end
+  
+  if k < 0
+    return ""
+  else
+    return_statement = strings[0][0...k]
+    return return_statement
+  end
 end
-