Ports - Sopheary

lib/array_intersection.rb

@@ -1,6 +1,22 @@
 # Returns a new array to that contains elements in the intersection of the two input arrays
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n x m) where n is the length of array1, and m is the length
+# of array2 since the method loops through both arrays.
+# Space complexity: O(n) because the intersection array stores the output.
+# Other strategies: I was trying to apply binary search to replace the second inner loop
+# but could not get it work because of infinite looping.
 def intersection(array1, array2)
-  raise NotImplementedError
+  return [] if array1.nil? || array2.nil? || array1 == [] || array2 == []
+  return [] if array1 == [] && array2 == []
+  return array1 if array1 == array2
+
+  intersection = []
+  array1.each do |i|
+    array2.each do |j|
+      intersection << i if i == j
+    end
+  end
+
+  return intersection
 end
+
+p

specs/array_intersection_spec.rb

@@ -1,6 +1,6 @@
-require 'minitest/autorun'
-require 'minitest/reporters'
-require_relative '../lib/array_intersection'
+require "minitest/autorun"
+require "minitest/reporters"
+require_relative "../lib/array_intersection"
 
 describe "array intersection" do
   describe "basic tests" do