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### by Sumit Chourasia | Oct 06, 2020 | Category :coding | Tags : algorithmbit-manipulationdata-structureeasyleetcode #### Number Complement - Bit Manipulation - Easy - LeetCode

Given a positive integer num, output its complement number. The complement strategy is to flip the bits of its binary representation.

Example 1:

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:

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.

Constraints:

The given integer num is guaranteed to fit within the range of a 32-bit signed integer.
num >= 1
You could assume no leading zero bit in the integer’s binary representation.
This question is the same as 1009: https://leetcode.com/problems/complement-of-base-10-integer/

``````public class Solution {
public int FindComplement(int num) {
int sum = 0;
for(int i=0;i<32 && num != 0;i++){
sum+=(int)Math.Pow(2,i)*((num&1)^1);
num=num>>1;
}
return sum;
}
}``````

Time Complexity: O(logn) which corresponds to the number of bits in the number.

Space Complexity: O(1)