diff --git a/lib/array_intersection.rb b/lib/array_intersection.rb
index ac8771f..7144eb7 100644
--- a/lib/array_intersection.rb
+++ b/lib/array_intersection.rb
@@ -1,3 +1,19 @@
+
+# Design and implement a method that takes two integer arrays
+# with unique values and returns their intersection in a new array.
+# Note: Do not use the & operator.
+
 def intersection(list1, list2)
-  raise NotImplementedError, "Intersection not implemented"
+  hash = {}
+  result = []
+  list1.each do |num|
+    hash[num] = true
+  end
+
+  list2.each do |i|
+    if hash[i] == true
+      result << i 
+    end 
+  end 
+  return result
 end
\ No newline at end of file
diff --git a/lib/palindrome_permutation.rb b/lib/palindrome_permutation.rb
index f113692..f0e7c84 100644
--- a/lib/palindrome_permutation.rb
+++ b/lib/palindrome_permutation.rb
@@ -1,4 +1,32 @@
+# Write a method which will take two strings as arguments 
+# and returns true if one string is a permutation of the other.
 
 def palindrome_permutation?(string)
-  raise NotImplementedError, "palindrome_permutation? not implemented"
+  hash = {}
+  count = 0
+
+  if string.empty?
+    return true
+  end
+
+  string.each_char do |i|
+    if hash[i] == nil
+      hash[i] = 1
+    else
+      hash[i] += 1
+    end
+  end
+
+  string_array = hash.values
+  string_array.each do |num|
+    if num.odd? == true
+      count += 1
+      if count > 1
+        return false
+      end
+    end
+  end
+  return true
+
+
 end
\ No newline at end of file
diff --git a/lib/permutations.rb b/lib/permutations.rb
index 3b08381..135af28 100644
--- a/lib/permutations.rb
+++ b/lib/permutations.rb
@@ -1,4 +1,25 @@
 
 def permutations?(string1, string2)
-  raise NotImplementedError, "permutations? not implemented"
+
+  hash = {}
+  if string1.length != string2.length
+    return false
+  end
+
+  string1.each_char do |letter|
+    if hash[letter]
+      hash[letter] += 1
+    else
+      hash[letter] = 1
+    end
+  end
+
+  string2.each_char do |letter|
+    if hash[letter] && hash[letter] != 0 
+      hash[letter] -= 1
+    else
+      return false
+    end
+  end
+  return true
 end
\ No newline at end of file