[leetcode] 1493. Longest Subarray of 1's After Deleting One Element _ Algorithm Problem Solve for python

1. Problem

1493. Longest Subarray of 1’s After Deleting One Element

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.

Constraints:

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

2. Solution

I solved this problem like this.

• Solve the problem with sliding window!

2.1. Solution1

• Check used zero count. If zero count is more bigger than k(max zero count),

class Solution:
    def longestSubarray(self, nums: List[int]) -> int:
        used_zero = l = ans = 0
        k = 1
        for r in range(len(nums)):
            if nums[r] == 0:
                used_zero += 1

            while used_zero > k:
                if nums[l] == 0:
                    used_zero -= 1
                l += 1
            ans = max(ans, r - l)
        return ans

2.2. Solution2

• Minus k value, if now idx value is 0.
• if k is smaller than 0, move left and plus k value if left is 0.
• return r - l. Once the maximum length is determined, the r - l value is also equal to the maximum length.

class Solution:
    def longestSubarray(self, nums: List[int]) -> int:
        k = 1
        l = 0
        for r in range(len(nums)):
            if nums[r] == 0:
                k-=1
            if k < 0:
                if nums[l] == 0:
                    k += 1
                l += 1

        return r - l