Space - Antonia

lib/array_intersection.rb

@@ -1,3 +1,19 @@
 def intersection(list1, list2)
-  raise NotImplementedError, "Intersection not implemented"
+  return [] if list1 == nil || list2 == nil
+
+  hash = {}
+
+  list1.each do |element|
+    hash[element] = true
+  end
+
+  result = []
+
+  list2.each do |number|
+    if hash.has_key?(number)
+      result << number
+    end
+  end
+  result
+
 end

lib/palindrome_permutation.rb

@@ -1,4 +1,25 @@
 
 def palindrome_permutation?(string)
-  raise NotImplementedError, "palindrome_permutation? not implemented"
+  return true if string.empty?
+
+  hash = {}
+
+  string.split("").each do |letter|
+    if hash[letter].nil?
+      hash[letter] = 1
+    else
+      hash[letter] += 1
+    end
+  end
+
+  odd = 0
+
+  hash.values.each do |v|
+    odd += 1 if v.odd?
+  end
+  if odd <= 1
+    return true
+  else
+    return false
+  end
 end

lib/permutations.rb

@@ -1,4 +1,26 @@
-
 def permutations?(string1, string2)
-  raise NotImplementedError, "permutations? not implemented"
+  return true if string1 == string2
+  return false if string1.length != string2.length
+
+  hash = {}
+
+  string1.split('').each do |letter|
+    if hash[letter]
+      hash[letter] += 1
+    else
+      hash[letter] = 1
+    end
+  end
+
+  string2.split('').each do |letter|
+    return false if !hash.key?(letter)
+    if hash[letter] > 0
+      hash[letter] -= 1
+    else
+      return false
+    end
+  end
+
+  return true
+
 end

test/palindrome_permutation_test.rb

@@ -1,6 +1,6 @@
 require_relative "test_helper"
 
-xdescribe "palindrome_permutation?" do
+describe "palindrome_permutation?" do
   it "will work for hello" do
     expect(palindrome_permutation?("hello")).must_equal false
   end

test/permutations_test.rb

@@ -1,6 +1,6 @@
 require_relative "test_helper"
 
-xdescribe "permutations?" do
+describe "permutations?" do
   it "returns true for empty string" do
     expect(permutations?("", "")).must_equal true
   end