tests = int(input())
value = []
for i in range(tests):
    stores = int(input())
    positions = input()
    positions = positions.split(' ')
    position_int = []

    for position in positions:
        position_int.append(int(position))

    value.append((max(position_int)-min(position_int))*2)

for val in value:
    print(val)