485. Max Consecutive Ones

Given a binary array, find the maximum number of consecutive 1s in this array.

Example 1:

Input: [1,1,0,1,1,1]
Output: 3
Explanation: The first two digits or the last three digits are consecutive 1s.
    The maximum number of consecutive 1s is 3.

Note:

• The input array will only contain 0 and 1.
• The length of input array is a positive integer and will not exceed 10,000

Solution 1: loop

class Solution:
    def findMaxConsecutiveOnes(self, nums: List[int]) -> int:
        count_global = 0
        count_cur = 0
        for i in nums:
            if i == 1:
                count_cur += 1
            else:
                if count_cur > count_global:
                    count_global = count_cur
                count_cur = 0
        return max(count_global, count_cur)

This beats 65.74 % of python3 submissions.

Solution 2: itertools.groupby

If we use the `itertools.groupby`, it would be much easier.

class Solution:
    def findMaxConsecutiveOnes(self, nums: List[int]) -> int:
        if 1 not in nums: return 0
        groups = [(key, len(list(group))) for key, group in itertools.groupby(nums) if key == 1] # [(1, 2), (0, 1), (1, 3)]
        return max(groups, key=lambda s: s[1])[1]

This solution is very fast, which beats 93.44 % of python3 submissions.