Create count-triplets-with-even-xor-set-bits-ii.py

Author: kamyu104

Python/count-triplets-with-even-xor-set-bits-ii.py

@@ -0,0 +1,45 @@
+# Time:  O(nlogr), r = max(max(a), max(b), max(c))
+# Space: O(1)
+
+# bit manipulation, parity
+class Solution(object):
+    def tripletCount(self, a, b, c):
+        """
+        :type a: List[int]
+        :type b: List[int]
+        :type c: List[int]
+        :rtype: int
+        """
+        def popcount(x):
+            return bin(x).count('1')
+
+        def count(a):
+            odd = sum(popcount(x)&1 for x in a)
+            return [len(a)-odd, odd]
+        
+        cnt = map(count, (a, b, c))
+        return sum(cnt[0][0 if i == 0 or i == 1 else 1]*cnt[1][0 if i == 0 or i == 2 else 1]*cnt[2][0 if i == 0 or i == 3 else 1] for i in xrange(4))
+    
+
+# Time:  O(nlogr), r = max(max(a), max(b), max(c))
+# Space: O(1)
+# bit manipulation, parity
+class Solution2(object):
+    def tripletCount(self, a, b, c):
+        """
+        :type a: List[int]
+        :type b: List[int]
+        :type c: List[int]
+        :rtype: int
+        """
+        def popcount(x):
+            return bin(x).count('1')
+
+        def count(a):
+            odd = sum(popcount(x)&1 for x in a)
+            return [len(a)-odd, odd]
+        
+        even1, odd1 = count(a)
+        even2, odd2 = count(b)
+        even3, odd3 = count(c)
+        return even1*even2*even3 + even1*odd2*odd3 + odd1*even2*odd3 + odd1*odd2*even3