191. Number of 1 Bits

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).

For example, the 32-bit integer ’11' has binary representation 00000000000000000000000000001011, so the function should return 3.

/*

java中有三种移位运算符

<<      :     左移运算符，num << 1,相当于num乘以2

>>      :     右移运算符，num >> 1,相当于num除以2

>>>    :     无符号右移，忽略符号位，空位都以0补齐

*/


public class Solution {
    // you need to treat n as an unsigned value
    public int hammingWeight(int n) {
        
       int ones = 0;
        while(n!=0) {
            ones = ones + (n & 1);
            n = n>>>1;
        }
        return ones;
    }
    
    
}