力扣 338. 比特位计数

解法1

def countBits(n):
    def count(x):
        if x == 0: return 0
        count_ = 0
        while x > 0:
            x &= (x - 1)
            count_ += 1
        return count_
    ret = []
    for i in range(n + 1):
        ret.append(count(i)) 
    return ret