476. Number Complement¶

#
# @lc app=leetcode id=476 lang=python3
#
# [476] Number Complement
#
# https://leetcode.com/problems/number-complement/description/
#
# algorithms
# Easy (67.36%)
# Likes:    2569
# Dislikes: 118
# Total Accepted:    310.5K
# Total Submissions: 459.9K
# Testcase Example:  '5'
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# The complement of an integer is the integer you get when you flip all the 0's
# to 1's and all the 1's to 0's in its binary representation.
#
#
# For example, The integer 5 is "101" in binary and its complement is "010"
# which is the integer 2.
#
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# Given an integer num, return its complement.
#
#
# Example 1:
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# Input: num = 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.
#
#
# Example 2:
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# Input: num = 1
# Output: 0
# Explanation: The binary representation of 1 is 1 (no leading zero bits), and
# its complement is 0. So you need to output 0.
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#
#
# Constraints:
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# 1 <= num < 2^31
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#
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# Note: This question is the same as 1009:
# https://leetcode.com/problems/complement-of-base-10-integer/
#
#

# @lc code=start
class Solution:
    def findComplement(self, num: int) -> int:

        r = 0

        i = 0

        while num:

            num, x = divmod(num, 2)

            r += (0 if x == 1 else 1)*2**i

            i += 1

        return r

# @lc code=end