461. Hamming Distance

The Hamming distance between two integers is the number of positions at which the corresponding bits are different.

Given two integers x and y, calculate the Hamming distance.

求x y的汉明距离，x和y按位异或得到的二进制，有多少个1就是结果。

C++(3ms):

 1 class Solution {
 2 public:
 3     int hammingDistance(int x, int y) {
 4         int t = x^y ;
 5         int sum = 0 ;
 6         while(t){
 7             t = (t-1)&t; 
 8             sum++ ;
 9         }
10         return sum ;
11     }
12 };

C++（6ms）：

 1 class Solution {
 2 public:
 3     int hammingDistance(int x, int y) {
 4          int t = x^y;
 5          int num = 0 ;
 6          while(t>0){
 7             if (t&1==1)
 8                 num++;
 9             t>>=1;
10          }
11          return num ;
12     }
13 };

C++（3ms）：

 1 class Solution {
 2 public:
 3     int hammingDistance(int x, int y) {
 4         int t = x^y;
 5         int num = 0 ;
 6         while(t>0){
 7             if (t%2==1)
 8               num++ ;
 9             t/=2;
10         }
11         return num;
12     }
13 };

C++（3ms）：

1 class Solution {
2 public:
3     int hammingDistance(int x, int y) {
4          return __builtin_popcount(x^y);
5     }
6 };

java（11ms）：

1 public class Solution {
2     public int hammingDistance(int x, int y) {
3         int t = x^y ;
4         return Integer.bitCount(t);
5     }
6 }