integer palindrome tests passing

lib/integer_palindrome_check.rb

@@ -1,4 +1,32 @@
 # Returns true if the input positive integer number forms a palindrome. Returns false otherwise.
+require 'pry'
 def is_palindrome(number)
-  raise NotImplementedError
+  return false if number == nil || number < 0
+  return true if number == 0
+
+  reversed_num = 0  # n
+  duplicate = number # n
+
+  while duplicate > 0
+    reversed_num *= 10
+    last_num = duplicate % 10 # only contains 1 digit at a time
+    reversed_num += last_num
+    duplicate -= last_num
+    duplicate /= 10
+  end
+
+  if number == reversed_num
+    return true
+  else
+    return false
+  end
 end
+
+#Time complexity: O(n) where n is the length/size of the input.
+#Depending on how many digits the number is the while loop will
+# continue to execute O(n - 1), but we drop the 1 because it is insignificant.
+
+#Space complexity: O(n) where n is the length/size of the input.
+# In this solution I defined 3 variables, 2 of which take
+#up the same space as the input's length. The last_num variable only
+#holds one digit at a time

specs/integer_palindrome_check_spec.rb

@@ -23,7 +23,7 @@
     it "nil object is not an integer" do
       is_palindrome(nil).must_equal false
     end
-
+  
     it "single digit palindrome" do
       is_palindrome(9).must_equal true
     end