Create xor-operation-in-an-array.py

Author: kamyu104

Python/xor-operation-in-an-array.py

@@ -0,0 +1,31 @@
+# Time:  O(1)
+# Space: O(1)
+
+class Solution(object):
+    def xorOperation(self, n, start):
+        """
+        :type n: int
+        :type start: int
+        :rtype: int
+        """
+        def xorNums(n, start):
+            def xorNumsBeginEven(n, start):
+                assert(start%2 == 0)
+                # 2*i ^ (2*i+1) = 1
+                return ((n//2)%2)^((start+n-1) if (n%2) else 0)
+
+            return start^xorNumsBeginEven(n-1, start+1) if start%2 else xorNumsBeginEven(n, start)
+        
+        return int(n%2 and start%2) + 2*xorNums(n, start//2)
+
+
+# Time:  O(n)
+# Space: O(1)
+class Solution2(object):
+    def xorOperation(self, n, start):
+        """
+        :type n: int
+        :type start: int
+        :rtype: int
+        """
+        return reduce(operator.xor, (i for i in xrange(start, start+2*n, 2)))