1、題目：

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:
For num = 5 you should return [0,1,1,2,1,2].

2、解答：    就是一個十進位制數轉換為二進位制的過程。除2取餘    f[i] = f[i/2] + i%2;

3、程式碼

C++程式碼

class Solution {
public:
    vector<int> countBits(int num) {
        vector<int> f(num+1,0);
        for(int i=1;i<=num;i++)
            f[i] = f[i>>1] + (i&1);
        return f;
    }
};
 

python程式碼

class Solution:
    def countBits(self, num):
        """
        :type num: int
        :rtype: List[int]
        """
    
        f = [0]*(num+1)
        for i in range(1,num+1):
            f[i] = f[i>>1] + (i&1)
        return f