868. Binary Gap 二进制间距

@TOC

# 题目描述

Given a positive integer N, find and return the longest distance between two consecutive 1's in the binary representation of N.

If there aren't two consecutive 1's, return 0.

Example 1:

``````Input: 22
Output: 2
Explanation:
22 in binary is 0b10110.
In the binary representation of 22, there are three ones, and two consecutive pairs of 1's.
The first consecutive pair of 1's have distance 2.
The second consecutive pair of 1's have distance 1.
The answer is the largest of these two distances, which is 2.
``````

Example 2:

``````Input: 5
Output: 2
Explanation:
5 in binary is 0b101.
``````

Example 3:

``````Input: 6
Output: 1
Explanation:
6 in binary is 0b110.
``````

Example 4:

``````Input: 8
Output: 0
Explanation:
8 in binary is 0b1000.
There aren't any consecutive pairs of 1's in the binary representation of 8, so we return 0.
``````

Note:

• 1 <= N <= 10^9

# 解题方法

# 线性扫描

``````class Solution(object):
def binaryGap(self, N):
"""
:type N: int
:rtype: int
"""
binary = bin(N)[2:]
dists = [0] * len(binary)
left = 0
for i, b in enumerate(binary):
if b == '1':
dists[i] = i - left
left = i
return max(dists)
``````

``````class Solution:
def binaryGap(self, N):
"""
:type N: int
:rtype: int
"""
nbins = bin(N)[2:]
index = -1
res = 0
for i, b in enumerate(nbins):
if b == "1":
if index != -1:
res = max(res, i - index)
index = i
return res
``````

# 日期

2018 年 7 月 17 日 —— 连天大雨，这种情况很少见，但是很舒服 2018 年 11 月 8 日 —— 项目进展缓慢