338. Counting Bits——dp
0-num中每个二进制数中1的个数
class Solution(object):
def countBits(self, num):
"""
:type num: int
:rtype: List[int]
"""
dp = [0]
for i in range(1, num + 1):
dp.append(dp[i & (i-1)] + 1)
return dp