number complement in bitmasking added

Author: Komal97

Bitmasking/number_complement.py

@@ -0,0 +1,44 @@
+'''
+https://leetcode.com/problems/number-complement/
+Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.
+
+Example 1:
+Input: 5
+Output: 2
+Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
+'''
+
+class Solution:
+    def countBits(self, num: int):
+        count = -1
+        while(num):
+            num = num >> 1
+            count += 1
+        return count
+        
+    # method - 1
+    def findComplement(self, num: int):
+        
+        c = self.countBits(num)
+        mask = 0
+        while(c>=0):
+            mask = mask | (1<<c)
+            c -= 1
+        
+        num = num ^ mask
+        
+        return num
+    
+    # method - 2
+    def findComplement(self, num: int):
+        
+        bit_count = self.countBits(num)
+        
+        # num = 5 = 101
+        # c = 3
+        # 2^3 = 8 = 1000 
+        # mask = 8-1 = 7 = 111
+        # num^mask = 101^111
+        
+        mask = (1 << (bit_count)) - 1
+        return num^mask