题目
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].
Follow up:
It is very easy to come up with a solution with run time O(n*sizeof(integer)). But can you do it in linear time O(n) /possibly in a single pass?
Space complexity should be O(n).
Can you do it like a boss? Do it without using any builtin function like __builtin_popcount in c++ or in any other language.
Credits:
Special thanks to @ syedee for adding this problem and creating all test cases.
分析
Code python
‘’’
class Solution(object):
def countBits(self, num):
“””
:type num: int
:rtype: List[int]
“””
result = []
‘’’
for i in range(num+1):
tmp = i
count = 0
while tmp != 0 :
count = count + tmp%2
tmp = tmp / 2
result.append(count)
‘’’
def func(num):
if num == 0 or num == 1:
return num
return ((num % 2) + func(num/2))
for i in range(num+1):
result.append(func(i))
return result
‘’’
