Time - Emily

lib/array_intersection.rb

@@ -1,3 +1,20 @@
 def intersection(list1, list2)
-  raise NotImplementedError, "Intersection not implemented"
+
+  intersections = {}
+
+  list1.each do |value|
+    if !intersections[value]
+      intersections[value] = 1
+    elsif intersections[value]
+      intersections[value] += 1
+    end
+  end
+
+  list2.each do |value|
+    if intersections[value]
+      intersections[value] += 1
+    end
+  end
+
+  return (intersections.select { |key, value| value == 2}).keys
 end

lib/palindrome_permutation.rb

@@ -1,4 +1,21 @@
 
 def palindrome_permutation?(string)
-  raise NotImplementedError, "palindrome_permutation? not implemented"
+  string_array = string.split("")
+  letter_instances = {}
+
+  string_array.each do |letter|
+    if !letter_instances[letter]
+      letter_instances[letter] = 1
+    else
+      letter_instances[letter] +=  1
+    end
+  end
+
+  duplicate_letters = letter_instances.select { |key, value| (value % 2) == 0}
+
+  if duplicate_letters.values.sum == string_array.length || duplicate_letters.values.sum == string_array.length - 1
+    return true
+  else
+    return false
+  end
 end

lib/permutations.rb

@@ -1,4 +1,26 @@
 
 def permutations?(string1, string2)
-  raise NotImplementedError, "permutations? not implemented"
+  intersections = {}
+  string1_array = string1.split("")
+  string2_array = string2.split("")
+
+  string1_array.each do |value|
+    if !intersections[value]
+      intersections[value] = 1
+    elsif intersections[value]
+      intersections[value] += 1
+    end
+  end
+
+  string2_array.each do |value|
+    if intersections[value]
+      intersections[value] += 1
+    end
+  end
+
+  if ((intersections.select { |key, value| (value % 2) == 0}).values.sum / 2) == string1_array.length
+    return true
+  else
+    return false
+  end
 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
@@ -9,7 +9,7 @@
     expect(permutations?("hello", "ehllo")).must_equal true
   end
 
-  it "returns true for 'heelo', 'ehllo'" do
+  it "returns false for 'heelo', 'ehllo'" do
     expect(permutations?("heelo", "ehllo")).must_equal false
   end
   it "returns true for 'pasta', 'atsap'" do