# 【LeetCode】 1493. Longest Subarray of 1's After Deleting One Element

## Description
> 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.

> Constraints:
> * `1 <= nums.length <= 10^5`
> * `nums[i]` is either `0` or `1`.

> 給一個二元陣列 `nums`，你必須刪除裡面其中一個元素。
> 回傳最長只包含 `1` 的非空子陣列。回傳 `0` 如果不存在這種子陣列。

> 限制：
> * `1 <= nums.length <= 10^5`
> * `nums[i]` 只會是 `0` 或是 `1`。

## Example:

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.

## Solution

* 先將原陣列換一個方式重新表達
* 改為紀錄目前 `1` 連續出現的次數
* `0` 代表間隔，將 `1` 的計數重置
* 例如 `[0,1,1,1,0,1,1,0,1]` 改為 `[0, 3, 2, 1]`
* 因為可以拿掉一個元素，代表可以將一個間隔去除
* 計算兩個次數的加總最多即為答案
* 需要注意的部分
* 結尾如果不是 `0`，也要將目前計數記下來
* 全部都是 `0`，要回傳 `0`
* 全部都是 `1`，要回傳數量減一(一樣得刪除一個)

### Code

class Solution {
public:
    int longestSubarray(vector<int>& nums) {
        vector<int> oneSeq;
        int counter = 0;
        for(int i = 0; i < nums.size(); i++)
        {
            if(nums[i] == 0)
            {
                oneSeq.push_back(counter);
                counter = 0;
            }
            else
            {
                counter++;
            }
        }
        if(oneSeq.empty())
        {
            if(counter == 0)
                return 0;
            else
            {
                return counter - 1;
            }
        }
        else
            oneSeq.push_back(counter);
            
        counter = oneSeq[0];
        for(int i = 0; i < oneSeq.size() - 1; i++)
        {
            counter = max(counter, oneSeq[i] + oneSeq[i + 1]);
        }
        return counter;

    }
};

###### tags: `LeetCode` `C++`