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.
题目：求32bit二进制数中1的个数.
1.int转为32bit二进制数
2.toBinaryString然后，count
1 public class Solution { 2 // you need to treat n as an unsigned value 3 public int hammingWeight(int n) { 4 5 Integer num = new Integer(n); 6 String s = num.toBinaryString(n); 7 System.out.println(s); 8 int count=0; 9 for(int i =0;i<s.length();i++){ 10 if(s.charAt(i)==‘1‘){ 11 count++; 12 // System.out.println(count); 13 } 14 } 15 16 return count; 17 } 18 }
248ms.
原文：http://www.cnblogs.com/catcoding/p/4707083.html