Sockets - Cyndi

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+m) ~= O(n) where n is the length of the larger array because the code iterates through each item in both of the arrays. Looking up items in a hash table is O(1) time complexity; therefore the linear time complexity is dependent on the size of the larger array.
+# Space complexity: O(n) - a new array is created to store intersecting values so space complexity is (worst-case) dependent on the length, n, of the array
 def intersection(array1, array2)
-  raise NotImplementedError
+  if array1.nil? || array2.nil? || array1 == [] || array2 == []
+    return []
+  end
+
+  new_hash = Hash.new
+  common_values = []
+  array1.each do |num|
+    new_hash[num] = 1
+  end
+
+  array2.each do |num|
+    if new_hash.include?(num)
+      common_values << num
+    end
+  end
+
+  return common_values
 end