diff --git a/lib/array_intersection.rb b/lib/array_intersection.rb
index ac8771f..ffb76f5 100644
--- a/lib/array_intersection.rb
+++ b/lib/array_intersection.rb
@@ -1,3 +1,19 @@
+
 def intersection(list1, list2)
-  raise NotImplementedError, "Intersection not implemented"
+  # raise NotImplementedError, "Intersection not implemented"
+  intersec_result = []
+
+  hash = {}
+
+  list1.each do |number|
+    hash[number] = true
+  end
+
+  list2.each do |number|
+    if !hash[number].nil?
+      intersec_result << number
+    end
+  end
+
+  return intersec_result
 end
\ No newline at end of file
diff --git a/lib/palindrome_permutation.rb b/lib/palindrome_permutation.rb
index f113692..eb68f60 100644
--- a/lib/palindrome_permutation.rb
+++ b/lib/palindrome_permutation.rb
@@ -1,4 +1,30 @@
 
+def count_chars_in_string (string)
+  hash = {}
+
+  string.each_char do |char|
+    if hash.key?(char) 
+      hash[char] += 1
+    else
+      hash[char] = 1
+    end
+  end
+  return hash
+end
+
+# the number of characters with odd number of occurences. 
+# If this countcount happens to exceed 1 at any step, 
+# we conclude that a palindromic permutation isn't possible for the string. 
+
 def palindrome_permutation?(string)
-  raise NotImplementedError, "palindrome_permutation? not implemented"
-end
\ No newline at end of file
+  # raise NotImplementedError, "palindrome_permutation? not implemented"
+
+  odd_ocurrences_count = 0
+  num_ocurrences_hash = count_chars_in_string(string)
+
+  num_ocurrences_hash.each do |key, value|
+    odd_ocurrences_count += value % 2
+  end
+  
+  return odd_ocurrences_count < 2
+end
diff --git a/lib/permutations.rb b/lib/permutations.rb
index 3b08381..b295719 100644
--- a/lib/permutations.rb
+++ b/lib/permutations.rb
@@ -1,4 +1,27 @@
 
+  
+def count_chars_in_string (string)
+  hash = {}
+
+  string.each_char do |char|
+    if hash.key?(char) 
+      hash[char] += 1
+    else
+      hash[char] = 1
+    end
+  end
+
+  return hash
+end
+
 def permutations?(string1, string2)
-  raise NotImplementedError, "permutations? not implemented"
-end
\ No newline at end of file
+  # raise NotImplementedError, "permutations? not implemented"
+  return false if string1.length != string2.length
+  # Return a boolean value.
+
+  hash_string1_counting = count_chars_in_string(string1)
+  hash_string2_counting = count_chars_in_string(string2)
+
+  return hash_string1_counting == hash_string2_counting
+
+end
diff --git a/test/palindrome_permutation_test.rb b/test/palindrome_permutation_test.rb
index e9119de..984b333 100644
--- a/test/palindrome_permutation_test.rb
+++ b/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
diff --git a/test/permutations_test.rb b/test/permutations_test.rb
index 79da2f6..dc3b865 100644
--- a/test/permutations_test.rb
+++ b/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
@@ -20,4 +20,8 @@
   it "returns false if the number of a specific letter are different" do
     expect(permutations?("pizza", "piza")).must_equal false
   end
+
+  it "returns false if the letter counts differ" do
+    expect(permutations?("pizza", "ppiza")).must_equal false
+  end
 end
\ No newline at end of file