코딜리티 BinaryGap 파이썬 :level 1

문제

A binary gap within a positive integer N is any maximal sequence of consecutive zeros that is surrounded by ones at both ends in the binary representation of N.

For example, number 9 has binary representation 1001 and contains a binary gap of length 2. The number 529 has binary representation 1000010001 and contains two binary gaps: one of length 4 and one of length 3. The number 20 has binary representation 10100 and contains one binary gap of length 1. The number 15 has binary representation 1111 and has no binary gaps. The number 32 has binary representation 100000 and has no binary gaps.

Write a function:

def solution(N)

that, given a positive integer N, returns the length of its longest binary gap. The function should return 0 if N doesn't contain a binary gap.

For example, given N = 1041 the function should return 5, because N has binary representation 10000010001 and so its longest binary gap is of length 5. Given N = 32 the function should return 0, because N has binary representation '100000' and thus no binary gaps.

 

풀이법

• 우선 bin 함수를 활용해 숫자를 이진수로 바꿔준뒤 list 로 변환
• list 를 reverse 시켜( 지금 생각하면 그러지 않아도 됐네)  끝에 0을 제거함.
• 1로 split 해준 다음 , map 함수를 이용해 1 로 split 된 문자열의 개수 리스트를 구한뒤 max binary gap 을 구함.

 

def solution(N):
    # write your code in Python 3.6
    test1=list(str(bin(N))[2:])
    longest_gap=0
    test1.reverse()
    import collections
    test1=collections.deque(test1)
    while(test1[0]=='0'):
        test1.popleft()
    test1=''.join(list(test1))
    test2=list(test1.split("1"))
    
    test2=list(map(returnlen,test2))
    return max(test2)

def returnlen(a):
    return len(a)