/*
 * @lc app=leetcode id=1009 lang=rust
 *
 * [1009] Complement of Base 10 Integer
 *
 * https://leetcode.com/problems/complement-of-base-10-integer/description/
 *
 * algorithms
 * Easy (59.47%)
 * Total Accepted:    20.1K
 * Total Submissions: 33.7K
 * Testcase Example:  '5'
 *
 * 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
 * 
 * 
 * 
 * 
 */
impl Solution {
    pub fn bitwise_complement(n: i32) -> i32 {
        if n == 0 { return 1; }
        let mut res = 0; 
        let mut m = n; 
        let mut i = 0 ; 
        while m > 1 {
            if m & 1 == 0 {
                res = 2_i32.pow(i) + res; 
            }
            // println!("{:?}", (i, tmp, res));
            i += 1;
            m = m / 2; 
        }
        res 
        // return res as i32; 
    }
}

// pub structSolution;