Hamming Distance

[hangzz]

Hamming Distance

example

Input: x = 1, y = 4

Output: 2

Explanation:
1   (0 0 0 1)
4   (0 1 0 0)
       ↑   ↑

answer

//主要就是几个位操作符
var hammingDistance = function(x, y) {
    var a = x ^ y;
    var count = 0 ;
    while ( a ) {
        if (a & 1){
             count ++;
         }
         a = a >> 1;
    }
    return count;
};

Number Complement

example

Input: 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.

answer

var findComplement = function(num) {
    var l = num.toString(2).length;
    var _num =Math.pow(2,l)-1;
    return num^_num
};

var findComplement = function(num) {
  var mask = ~0;   
  while (mask & num) { 
    mask = mask << 1; 
  } 
  return ~(mask ^ num);    
};