1009 Complement of Base 10 Integer.py

Author: rajeevranjancom

1009 Complement of Base 10 Integer.py

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+#!/usr/bin/python3
+"""
+Every non-negative integer N has a binary representation.  For example, 5 can be
+represented as "101" in binary, 11 as "1011" in binary, and so on.  Note that
+except for N = 0, there are no leading zeroes in any binary representation.
+
+The complement of a binary representation is the number in binary you get when
+changing every 1 to a 0 and 0 to a 1.  For example, the complement of "101" in
+binary is "010" in binary.
+
+For a given number N in base-10, return the complement of it's binary
+representation as a base-10 integer.
+
+Example 1:
+Input: 5
+Output: 2
+Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2
+in base-10.
+
+Example 2:
+Input: 7
+Output: 0
+Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0
+in base-10.
+
+Example 3:
+Input: 10
+Output: 5
+Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is
+5 in base-10.
+
+Note:
+0 <= N < 10^9
+"""
+
+
+class Solution:
+    def bitwiseComplement(self, N: int) -> int:
+        """
+        invert the bit, and the mask it
+        """
+        mask = 1
+        cur = N
+        while cur >> 1:
+            cur >>= 1
+            mask <<= 1
+            mask += 1
+
+        return ~N & mask