Given a circular array C of integers represented by A, find the maximum possible sum of a non-empty subarray of C.
Here, a circular array means the end of the array connects to the beginning of the array.  (Formally, C[i] = A[i] when 0 <= i < A.length, and C[i+A.length] = C[i] when i >= 0.)
Also, a subarray may only include each element of the fixed buffer A at most once.  (Formally, for a subarray C[i], C[i+1], ..., C[j], there does not exist i <= k1, k2 <= j with k1 % A.length = k2 % A.length.)
 

Example 1:
Input: [1,-2,3,-2]
Output: 3
Explanation: Subarray [3] has maximum sum 3


Example 2:
Input: [5,-3,5]
Output: 10
Explanation: Subarray [5,5] has maximum sum 5 + 5 = 10


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


Example 4:
Input: [3,-2,2,-3]
Output: 3
Explanation: Subarray [3] and [3,-2,2] both have maximum sum 3

Example 5:
Input: [-2,-3,-1]
Output: -1
Explanation: Subarray [-1] has maximum sum -1

 
Note: 

-30000 <= A[i] <= 30000
1 <= A.length <= 30000

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'class Solution:\n    def maxSubarraySumCircular(self, A: List[int]) -> int:\n        N = len(A)\n\n        ans = cur = 0\n        for x in A:\n            cur = x + max(cur, 0)\n            ans = max(ans, cur)\n\n        rightsums = [None] * N\n        rightsums[-1] = A[-1]\n        for i in range(N-2, -1, -1):\n            rightsums[i] = rightsums[i+1] + A[i]\n\n        # maxright[i] = max_{j >= i} rightsums[j]\n        maxright = [None] * N\n        maxright[-1] = rightsums[-1]\n        for i in range(N-2, -1, -1):\n            maxright[i] = max(maxright[i+1], rightsums[i])\n\n        leftsum = 0\n        for i in range(N-2):\n            leftsum += A[i]\n            ans = max(ans, leftsum + maxright[i+1])\n        if max(A) < 0:\n            return max(A)\n        return ans\n    \n    \n#         total = sum(A)\n#         max_sum_ending_i = [A[0]]\n#         prev = max_sum_ending_i[-1]\n        \n        \n#         for i in range(1, len(A)):\n#             if prev <= 0:\n#                 max_sum_ending_i.append(A[i])\n#             else:\n#                 max_sum_ending_i.append(max_sum_ending_i[-1]+A[i])\n#             prev = max_sum_ending_i[-1]\n        \n#         min_sum_ending_i = [A[0]]\n#         prev = min_sum_ending_i[-1]\n\n#         for i in range(1, len(A)):\n#             if prev >= 0:\n#                 min_sum_ending_i.append(A[i])\n#             else:\n#                 min_sum_ending_i.append(min_sum_ending_i[-1]+A[i])\n#             prev = min_sum_ending_i[-1]\n        \n#         if max(A) > 0:\n#             return max(total - min(min_sum_ending_i), max(max_sum_ending_i))\n#         else:\n#             return max(A)\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'maxSubarraySumCircular'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 5962