# Leetcode: Complement of Base 10 Integer

Complement of Base 10 Integer Similar Problems:

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

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

• Solution:
```// Blog link: https://code.dennyzhang.com/complement-of-base-10-integer
// Basic Ideas: bit map
// Complexity: Time O(1), Space O(1)
func bitwiseComplement(N int) int {
if N == 0 { return 1 }
k := 1
for k <= N {
k = k*2
}
k = k-1
return ^N & k
}
```

Share It, If You Like It.