按方案中的第一个元素对列表进行排序

问题描述

我正在按列表的第一个元素对列表进行排序，例如
(排序 (列表 '(2 1 6 7) '(4 3 1 2 4 5) '(1 1))))

I'm working on sorting a list of lists by their first element for example
(sort (list '(2 1 6 7) '(4 3 1 2 4 5) '(1 1))))

预期输出 => ('(1 1) '(2 1 6 7) '(4 3 1 2 4 5))

expected output => ('(1 1) '(2 1 6 7) '(4 3 1 2 4 5))

我使用的算法是冒泡排序.我修改了它来处理列表.但是，代码无法编译.错误是

The algorithm I used is bubble sort. And I modified it to deal with lists. However, the code doesn't compile. The error is

mcar: contract violation
  expected: mpair?
  given: 4

谁能更正我的代码并解释一下.谢谢

Can someone correct my code and explain it. Thank you

 (define (bubble L)
        (if (null? (cdr L))
            L
            (if (< (car (car L)) (car (cadr L)))
                (list (car L)
                      (bubble (car (cdr L))))
                (list (cadr L)
                      (bubble (cons (car (car L)) (car (cddr L))))))))

    (define (bubble-sort N L)
        (cond ((= N 1) (bubble L))
              (else
               (bubble-sort (- N 1) (bubble L)))))

    (define (bubble-set-up L)
        (bubble-sort (length L) L))


    (define t3 (list '(2 1 6 7) '(4 3 1 2 4 5) '(1 2 3) '(1 1)))
    (bubble-set-up t3)

推荐答案

我修正了一些错误.至少还剩下一个错误.考虑 L 只包含一个元素的情况.

I have fixed a few mistakes. There is at least one mistake left.Consider the case where L only contains one element.

#lang r5rs

(define (bubble L)
  (if (null? (cdr L))
      L
      (if (< (car (car L)) (car (cadr L)))
          (cons (car L)
                (bubble (cdr L)))
          (cons (cadr L)
                (bubble (cons (car L) (cddr L)))))))

(define (bubble-sort N L)
  (cond ((= N 1) (bubble L))
        (else
         (bubble-sort (- N 1) (bubble L)))))

(define (bubble-set-up L)
  (bubble-sort (length L) L))


(define t3 (list '(2 1 6 7) '(4 3 1 2 4 5) '(1 2 3) '(1 1)))
(display (bubble-set-up t3))
(newline)

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