题目描述：
Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.
Example 1:
Input: 2
Output: [0,1,1]Example 2:
Input: 5
Output: [0,1,1,2,1,2]题目大意：计算0-num中每个数所对应的二进制中1的个数
解题思路：简单粗暴，利用Java已有的API直接解决
class Solution {
public int[] countBits(int num) {
int[] arr = new int[num+1];
for(int i=0;i<num+1;i++){
arr[i] = Integer.bitCount(i);
}
return arr;
}
}