1 package com.wang.test;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 /* @Tittle
 7  * 338. Counting Bits
 8  * Given a non negative integer number num. 
 9  * For every numbers i in the range 0 ≤ i ≤ num 
10  * calculate the number of 1's in their binary representation and return them as an array.
11  * @auther:wanglin
12  * @time:2016/04/11
13  */
14 public class CountingBits {
15     public int[] countBits(int num) {
16         List list = new ArrayList();
17         for (int n = 0; n <= num; ++n) {
18             // binaryNum接收转为二进制的数字
19             String binaryNum = Integer.toBinaryString(n);
20             char[] charArr = binaryNum.toCharArray();
21             int i = 0;
22             for (int m = 0; m < charArr.length; ++m) {
23                 if (charArr[m] == '1') {
24                     i++;
25                 }
26             }
27             list.add(i);
28         }
29         int[] res = new int[list.size()];
30         for (int i = 0; i < list.size(); i++) {
31             res[i] = (Integer) list.get(i);
32         }
33         return res;
34     }
35 
36     public static void main(String[] args) {
37         int[] res = new CountingBits().countBits(5);
38         for (int i : res) {
39             System.out.print(i);
40         }
41     }
42 }