Find if a list of int can be sorted by only one swap

is_one_swap_can_sort.py

def is_one_swap_can_sort(nums):
    sorted_nums = sorted(nums)
    if nums == sorted_nums:
        return True

    len_nums = len(nums)
    for i in range(len_nums):
        for j in range(i+1, len_nums):
            test = nums.copy()
            if test[i] > test[j]:
                temp = test[i]
                test[i] = test[j]
                test[j] = temp
            if test == sorted_nums:
                return True
    return False


questions_answers = [
    ([1,2,4,5,3], False),
    ([1,3,3,4,5], True),
    ([1,2,3,4,5], True),
    ([1,3,2,5,4], False),
    ([5,2,3,4,1], True),
    ([5,4,4,1,6], True), 
    ([2,6,6,5], True),
    ([5,6,6,1], False),
    ([1], True),
    ([], True),
]

for question, answer in questions_answers:
    myanswer = is_one_swap_can_sort(question)
    is_wrong = 'XXX' if myanswer != answer else ''
    print("{} => {} (Expected: {}) {}".format(question, myanswer, answer, is_wrong))

แก้แล้วๆ เพิ่ม test case เข้าไปอีกสองอัน คือกรณี list ว่าง กับ list มีสมาชิกตัวเดียว

This one by @9terz is more clever, sort then count differences:
https://gist.github.com/9terz/efa8d2b13840a7dfba07f5228af144e1

same logic with @salamtamp (in JavaScript):
https://gist.github.com/salamtamp/ed46781954d659f24dff223090fe5203