Time - Sharon Cheung

lib/array_intersection.rb

@@ -1,3 +1,17 @@
 def intersection(list1, list2)
-  raise NotImplementedError, "Intersection not implemented"
+  count_hash = {}
+  result = []
+
+  list1.each do |number|
+    count_hash[number] = true
+  end
+
+  list2.each do |number|
+    if count_hash[number] == true
+      result << number
+    end
+  end
+
+  return result
+
 end

lib/palindrome_permutation.rb

@@ -1,4 +1,21 @@
 
 def palindrome_permutation?(string)
-  raise NotImplementedError, "palindrome_permutation? not implemented"
+  letter_hash = {}
+
+  string.split("").each do |letter|
+    if letter_hash[letter] == nil
+      letter_hash[letter] = 1
+    else
+      letter_hash[letter] += 1
+    end
+  end
+
+  midpoint = 0
+  letter_hash.each_value do |times|
+    if times % 2 != 0
+      midpoint += 0
+    end
+  end
+
+  return midpoint <= 1
 end

lib/permutations.rb

@@ -1,4 +1,28 @@
 
 def permutations?(string1, string2)
-  raise NotImplementedError, "permutations? not implemented"
+  word_hash = {}
+
+  string1.split("").each do |letter|
+    if word_hash[letter] == nil
+      word_hash[letter] = 1
+    else
+      word_hash[letter] += 1
+    end
+  end
+
+  string2.split("").each do |letter|
+    if word_hash[letter] == nil
+      return false
+    else
+      word_hash[letter] -= 1
+    end
+  end
+
+  word_hash.each_value do |times|
+    if times != 0
+      return false
+    end
+  end
+
+  return true
 end