LC969 Pancake Sorting

class Solution:
    def pancakeSort(self, A: List[int]) -> List[int]: 
        def swp(sub,k):
            i = 0
            mid = k //2
            while i < mid:
                sub[i], sub[k-i-1] = sub[k-i-1], sub[i]
                i += 1
        res = []
        val_sort = len(A)
        while val_sort > 0 :
            idx = A.index(val_sort)
            if idx != val_sort -1:
                if  idx != 0:
                    res.append(idx +1)
                    swp(A,idx+1)
                res.append(val_sort)
                swp(A, val_sort)
            val_sort -= 1
        return res