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Longest Subarray of 1's After Deleting One Element

LeetCode #: 1493

Difficulty: Medium

Topics: Array.

Problem

Given a binary array nums, you should delete one element from it.

Return the size of the longest non-empty subarray containing only 1's in the resulting array.

Return 0 if there is no such subarray.

Example 1:

Input: nums = [1,1,0,1]
Output: 3
Explanation: After deleting the number in position 2, [1,1,1] contains 3 numbers with value of 1's.

Example 2:

Input: nums = [0,1,1,1,0,1,1,0,1]
Output: 5
Explanation: After deleting the number in position 4, [0,1,1,1,1,1,0,1] longest subarray with value of 1's is [1,1,1,1,1].

Example 3:

Input: nums = [1,1,1]
Output: 2
Explanation: You must delete one element.

Example 4:

Input: nums = [1,1,0,0,1,1,1,0,1]
Output: 4

Example 5:

Input: nums = [0,0,0]
Output: 0

Constraints:

• 1 <= nums.length <= 10^5
• nums[i] is either 0 or 1.

Solution Explanation

Loop through all the numbers and keep track of the count in the groups of 1 and 0. You only need to keep track of the last two groups of 1 (prevCount1 and currCount1) and last one group of 0 (count0). You can combine prevCount1 and currCount1 when count0 is equal to 1.

Complexity Analysis

Time complexity: O(n)

Space complexity: O(1)