Angele Z.

lib/practice_exercises.rb

@@ -1,13 +1,59 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n) - it will always run however long the list is.
+# Space Complexity: O(1) - nothing new is created
 def remove_duplicates(list)
-  raise NotImplementedError, "Not implemented yet"
+
+  stored_item = nil
+  stored_index = 0
+  new_array_length = 0
+  current_index = 0
+
+  if list.length <= 1
+    return list
+  end
+
+  if list.length > 1
+    until list[current_index - 1] == list.last && stored_item != nil
+      if stored_item == nil
+        stored_item = list[current_index]
+        list[stored_index] = list[current_index]
+        new_array_length += 1
+        current_index += 1
+        stored_index += 1
+      elsif list[current_index] > stored_item
+        stored_item = list[current_index]
+        list[stored_index] = list[current_index]
+        new_array_length += 1
+        current_index += 1
+        stored_index += 1
+      elsif list[current_index] == stored_item
+        current_index += 1
+      end
+    end
+  end
+
+  return list[0,new_array_length]
+
 end
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n*m) - or O(shortest_string.length * strings.length)
+# Space Complexity: O(1) - 
 def longest_prefix(strings)
-  raise NotImplementedError, "Not implemented yet"
+  shortest_string = strings.min_by { |string| string.length }
+  current_index = 0
+
+  until current_index == shortest_string.length 
+    strings.each do |string|
+      if string[current_index] != shortest_string[current_index]
+        return shortest_string[0,current_index]
+      end
+    end
+
+    current_index += 1
+
+  end
+
+  return shortest_string[0,current_index]
+
 end
 

test/practice_exercises_test.rb

@@ -32,6 +32,14 @@
       expect(output).must_equal "f"
     end
 
+    it "returns the whole word if all match" do
+      strings = ["flower","flower","flower"]
+
+      output = longest_prefix(strings)
+
+      expect(output).must_equal "flower"
+    end
+
     it "will work for the README strings" do
       strings = ["dog","racecar","car"]