Number-of-1-Bits.md

##Number of 1 Bits Total Accepted: 77514 Total Submissions: 206348 Difficulty: Easy 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.

####思路

public class Solution {
    // you need to treat n as an unsigned value
    public int hammingWeight(int n) {
        int count = 0;
        for (int i = 0; i < 32; i++) {
            int a = n & (1 << i);
            if (a != 0) {
                count++;
            }

        }
        return count;
    }
}