485. Max Consecutive Ones@python

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.

原题地址: Max Consecutive Ones

难度: Easy

题意: 找出连续为1的子数组的最大长度

思路1:

因为只有0, 1,可以通过确定0的位置确定1的长度.但需要考虑边界问题,可以假设 -1位置 和 len(nums) 位置都为0,边界问题就可以解决了

索引:   0    1    2    3    4    5    6
数值:   1    1    1    1    0    1    1

变为:

索引:   -1    0    1    2    3    4    5    6
数值:    0    1    1    1    1    0    1    1    0
第一组连续1的子数组长度: 4 - (-1) - 1  = 4

第二组连续1的子数组长度: 7 - (4) - 1 = 2

代码:

class Solution(object):
    def findMaxConsecutiveOnes(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        j = -1        # 初始化0的位置
        res = 0
        for i in range(len(nums)):
            if nums[i] == 0:
                res = max(res, i-j-1)
                j = i
        res = max(res, len(nums)-j-1)
        return res

思路2:

遍历数组,统计1的个数

代码:

class Solution(object):
    def findMaxConsecutiveOnes(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        res = 0
        count = 0
        for i in range(len(nums)):
            if nums[i] == 1:
                count += 1
                res = res if res > count else count
            else:
                count = 0
        return res 

时间复杂度: O(n)

空间复杂度: O(1)