README.md

1009. Complement of Base 10 Integer

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:

1. 0 <= N < 10^9

Solutions (Rust)

1. Mathematical

implSolution{pubfnbitwise_complement(n:i32) -> i32{match n {0 => 1, _ => 2_i32.pow((n asf64).log2()asu32 + 1) - 1 - n,}}}

2. Bitwise Operator

implSolution{pubfnbitwise_complement(n:i32) -> i32{letmut ret = 0;for i in0..31{if n >> i == 0 && i > 0{break;}if n &(1 << i) == 0{ ret ^= 1 << i;}} ret }}