Create find-the-xor-of-numbers-which-appear-twice.py

Author: kamyu104

Python/find-the-xor-of-numbers-which-appear-twice.py

@@ -0,0 +1,27 @@
+# Time:  O(n)
+# Space: O(n)
+
+# hash table
+class Solution(object):
+    def duplicateNumbersXOR(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        return reduce(lambda x, y: x^y, nums, 0)^reduce(lambda x, y: x^y, set(nums), 0)
+
+
+# Time:  O(n)
+# Space: O(n)
+import collections
+
+
+# freq table
+class Solution2(object):
+    def duplicateNumbersXOR(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        return reduce(lambda x, y: x^y, (x for x, c in collections.Counter(nums).iteritems() if c == 2), 0)
+