Given a binary array nums, return the maximum number of consecutive 1's in the array.
Example 1:
Input: nums = [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.
Example 2:
Input: nums = [1,0,1,1,0,1]
Output: 2
Constraints:
1 <= nums.length <= 105
nums[i] is either 0 or 1.
Solutions
Solution 1: Single Pass
We can iterate through the array, using a variable $\textit{cnt}$ to record the current number of consecutive 1s, and another variable $\textit{ans}$ to record the maximum number of consecutive 1s.
When we encounter a 1, we increment $\textit{cnt}$ by one, and then update $\textit{ans}$ to be the maximum of $\textit{cnt}$ and $\textit{ans}$ itself, i.e., $\textit{ans} = \max(\textit{ans}, \textit{cnt})$. Otherwise, we reset $\textit{cnt}$ to 0.
After the iteration ends, we return the value of $\textit{ans}$.
The time complexity is $O(n)$, where $n$ is the length of the array. The space complexity is $O(1)$.