很简单的问题，最笨的算法，自己第一个用scheme写的稍微算长点的程序.

废话不多说，直接上代码.

(begin    (load "ex2.scm")    (define (make-maze)    (define (for-each proc things)        (cond ((null? things) nil)              (else                    (let ((ret (proc (car things))))                    (if (null? ret) (for-each proc (cdr things)) ret)))))    ;迷宫    (define maze  '((1 1 1 1 1 1 1 1 1)                    (1 0 1 0 0 0 1 0 1)                    (1 0 1 0 1 0 1 0 1)                    (1 0 1 0 1 0 1 0 1)                    (1 0 0 0 0 0 0 0 1)                    (1 1 1 1 1 1 1 1 1)))    (define direction '((0 -1)(0 1)(-1 0)(1 0))) ;上下左右    (define (get-x-y array-2d x y)        (list-ref (list-ref array-2d x) y))    (define (is-close cur path);是否已经走过的路            (= 1 (accumulate                 (lambda (pos sum)                 (if (and (= (car pos) (car cur)) (= (cadr pos) (cadr cur))) (+ sum 1) sum))              0 path)))    ;检查是否合法路径    (define (check cur dir path)        (let ((x (+ (car dir) (car cur)))              (y (+ (cadr dir) (cadr cur))))         (cond ((is-close (list x y) path) nil)               ((= (get-x-y maze x y) 1) nil);阻挡               (else (list x y)))))   ;返回下一步合法的坐标        ;返回一条路径    (define (find-path-one start target)        (define (iter cur-step path)            (define (move dir)                (let ((next (check cur-step (list-ref direction dir) path)))                    (cond ((null? next) nil)                          (else (iter next (cons cur-step path))))))                                      (if (and (= (car target) (car cur-step))                     (= (cadr target) (cadr cur-step))) (cons cur-step path)                (for-each move (enumerate-interval 0 3)))             )        (reverse (iter start nil))    )    ;返回所有路径    (define (find-path-all start target)            (define (iter cur-step path)            (define (move dir)                (let ((next (check cur-step (list-ref direction dir) path)))                    (cond ((null? next) nil)                          (else (iter next (cons cur-step path))))))                                      (cond ((and (= (car target) (car cur-step)) (= (cadr target) (cadr cur-step)))                 (list (cons cur-step path))) ;到达目的地，返回路劲                  (else                      (accumulate (lambda (dir p) (append (move dir) p)) nil (enumerate-interval 0 3))))        )        (map reverse (iter start nil))    )    (lambda (op start target)        (cond ((eq? op 'find-path-all) (find-path-all start target))              ((eq? op 'find-path-one) (find-path-one start target))              (else "bad op"))    ))    );(define maze make-maze);(maze 'find-path-one '(1 1) '(1 7))