Racket-按字母升序对字符串列表进行排序

因此，我试图编写自己的排序函数，以字母升序重新排列元素。 例如：

(check-expect (sort-list (list "ABD" "ABC" "BCE" "ADE") 0) 
              (list "ABC" "ABD" "ADE" "BCE"))

以下是我目前的情况：

(define (sort-list lst n)
  (cond
    [(empty? lst) empty]
    [else
     (cons
      (cond
       [(> (substring (first lst) n (+ n 1)) (substring (first (rest lst)) n (+ n 1))) (first (rest lst))]
       [else (sort-list (rest lst) (+ n 1))]))]))

---

有人能帮我修改代码，使其正常工作吗？

您可以使用插入排序。我将首先使用helper函数insert，其代码如下所示

(define (insert los sorted-los)
  (cond [(empty? sorted-los) (list los)]
        [(string<=? los (first sorted-los))
         (cons los sorted-los)]
        [else (cons (first sorted-los)
                    (insert los (rest sorted-los)))]))

(check-expect (sort-list (list "ABD" "ABC" "BCE" "ADE"))
              (list "ABC" "ABD" "ADE" "BCE"))

(check-expect (sort-list (list "ABF" "ABC" "BCE" "ADE"))
              (list "ABC" "ABF" "ADE" "BCE"))
(check-expect (sort-list (list "ABD" "ABC" "BCE" "EFG"))
              (list "ABC" "ABD" "BCE" "EFG"))

(check-expect (sort-list (list "ABC" "ABC" "BCG" "ADE"))
              (list "ABC" "ABC" "ADE" "BCG"))

---

为什么将

n

作为

排序列表的参数？那是干什么用的？因为您可以在不使用附加参数的情况下重新排列列表。“（排序列表字符串