插入排序问题——如何遍历每个数字？

Question

I wrote an insertion sort, but it doesn't sort all the numbers.

When I take out ' y = x - 1 ' and just put ' x - 1 ' in there on it's own, the algorithm works. With the variable, the algorithm doesn't work.

Please tell me the issue with this algorithm.

def insertsort(alist):
    for x in range(1, len(alist)):
        y = x-1
        while alist[y] > alist[x]:
            alist[y], alist[x] = alist[x], alist[y]
            x -= 1
            print(alist)



insertsort([1,2,5,7,4,11,8,75,54,101,99])

Answer 1

You probably should be doing your own homework, but, here you go:

def insertsort(a):
    print(a)
    # finish the sort from left to right
    for fin in range(1, len(a)):
        tst = fin
        # sort from tst down to zero, swapping curr tst w/ lower as needed
        while(tst > 0 and a[tst] < a[tst-1]):
            # swap
            a[tst], a[tst-1] = a[tst-1], a[tst]
            # follow tst down
            tst -= 1
            print(a)

insertsort([9,8,7,6,5,4,3,2,1])

Answer 2

1.It is unnecessary for x -= 1 ,maybe you can delete and run again. 2.Your sorting only done once. 3. (print(alist) ),this sentence should be aligned with (for...) ,it will get only one list. The code is as follows, for reference only.

def insertsort(alist):
    for x in range(1,len(alist)):
        for y in range(1,len(alist)):
            z = y-1
            while alist[z] > alist[y]:
                alist[z], alist[y] = alist[y], alist[z]
    print(alist)
insertsort([3,2,5,7,4,11,8,75,54,101,99])