BinaryGap

Codility Lessons 문제를 풀면서 정리합니다.

문제 설명

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:

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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.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [1..2,147,483,647]. Copyright 2009–2022 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

문제 요약

• 입력된 정수 N을 이진수(Binary)로 변환했을 때 1과 1 사이에 존재하는 0의 개수가 가장 큰 값을 반환합니다.
• 예를 들어 N이 1041인 경우, 이진수 변환 값은 10000010001이기 때문에 연속된 0의 개수가 5, 4개 입니다. 따라서 이 값중 가장 큰 값인 5를 반환합니다.

문제 풀이

• 문자열 이진수 형태로 변환한 후, 문제 조건에 따라 0의 개수를 체크합니다.

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def solution(N):
    # write your code in Python 3.6
    binary = str(bin(N))[2:]
    answers = list()
    counter = 0
    for bi in binary:
        if bi == "0":
            counter += 1
        elif bi == "1":
            answers.append(counter)
            counter = 0

    return max(answers)