第一体100% if __name__ == '__main__': cse = int(input()) for _ in range(cse): n = int(input()) li = list(map(int, input().split())) cnt_0 = 0 cnt_1 = 0 p1 = 0 p2 = 0 result = 0 flag_all_1 = True for e in li: if e == 0: flag_all_1 = False break while p1 < n: if cnt_0 <= 1 and p2 < n: if li[p2] == 0: p2 += 1 cnt_0 += 1 else: p2 += 1 cnt_1 += 1 else: if li[p1] == 0: cnt_0 -= 1 else: cnt_1 -= 1 p1 += 1 if cnt_1 > result: result = cnt_1 print(result if not flag_all_1 else result - 1)