Why my recursive solution occur a wrong answer error?it seems like a bug!

• The below is the testcase's input and output. When i test in my local environment, my code outputs the correct result [2,1], why the oj's output is [1,2]? it confused me for a long time.

Input: [1,2]
Output: [1,2]
Expected: [2,1]

here is my python solution, please help for me ,thanks!!

``````class Solution:
# @param num, a list of integer
# @return nothing (void), do not return anything, modify num in-place instead.
def nextPermutation(self, num, reverse = [], start = [], stackLayer = 0):
l = len(num)-stackLayer
index = -1
if l == 1:
reverse.append(1)
else:
for i in range(l-2, -1, -1):
if num[l-1] > num[i]:
num[l-1],num[i] = num[i],num[l-1]
index = i
start.append(index)
break
else:
pass
if index == -1:
self.nextPermutation(num,reverse,start,stackLayer+1)
if start != []:
index = start[0]
if reverse != [] and stackLayer == 0:
for i in range(0,l/2):
num[i],num[l-i-1] = num[l-i-1],num[i]
elif reverse == []:
for i in range(index+1,l-1):
if num[l-1] < num[i]:
num[l-1],num[i] = num[i],num[l-1]
else:
pass``````

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