# GeetCode Hub

Given a circular integer array `nums` of length `n`, return the maximum possible sum of a non-empty subarray of `nums`.

A circular array means the end of the array connects to the beginning of the array. Formally, the next element of `nums[i]` is `nums[(i + 1) % n]` and the previous element of `nums[i]` is `nums[(i - 1 + n) % n]`.

A subarray may only include each element of the fixed buffer `nums` at most once. Formally, for a subarray `nums[i], nums[i + 1], ..., nums[j]`, there does not exist `i <= k1`, `k2 <= j` with `k1 % n == k2 % n`.

Example 1:

```Input: nums = [1,-2,3,-2]
Output: 3
Explanation: Subarray  has maximum sum 3
```

Example 2:

```Input: nums = [5,-3,5]
Output: 10
Explanation: Subarray [5,5] has maximum sum 5 + 5 = 10
```

Example 3:

```Input: nums = [3,-1,2,-1]
Output: 4
Explanation: Subarray [2,-1,3] has maximum sum 2 + (-1) + 3 = 4
```

Example 4:

```Input: nums = [3,-2,2,-3]
Output: 3
Explanation: Subarray  and [3,-2,2] both have maximum sum 3
```

Example 5:

```Input: nums = [-2,-3,-1]
Output: -1
Explanation: Subarray [-1] has maximum sum -1
```

Constraints:

• `n == nums.length`
• `1 <= n <= 3 * 104`
• `-3 * 104 <= nums[i] <= 3 * 104`

class Solution { public int maxSubarraySumCircular(int[] nums) { } }