Hanoi Operations

plexho.clj

(defn hanoi-ops [s t d n]
  (if (zero? n) '()
      (concat
        (hanoi s d t (dec n))
        (list [n s d])
        (hanoi t s d (dec n)))))

(hanoi-ops 'A 'B 'C 4)
; -> ([1 A B] [2 A C] [1 B C] [3 A B] [1 C A] [2 C B] [1 A B] [4 A C]
;     [1 B C] [2 B A] [1 C A] [3 B C] [1 A B] [2 A C] [1 B C])

plexho.hs

hanoi_ops s t d	n
  | n == 0    = []
  | otherwise =	hanoi_ops s d t	(n - 1)	++
		[(n, s, d)] ++
      	      	hanoi_ops t s d	(n - 1)

hanoi_ops 'A' 'B' 'C' 4
-- -> [(1,'A','B'),(2,'A','C'),(1,'B','C'),(3,'A','B'),
--     (1,'C','A'),(2,'C','B'),(1,'A','B'),(4,'A','C'),
--     (1,'B','C'),(2,'B','A'),(1,'C','A'),(3,'B','C'),
--     (1,'A','B'),(2,'A','C'),(1,'B','C')]

plexho.js

function hanoi_ops(s, t, d, n) {
  if (0	< n)
    return hanoi_ops(s, d, t, n - 1).concat(
       	   [[n, s, d]]).concat(
       	   hanoi_ops(t, s, d, n - 1));
  return [];
}

hanoi_ops('A', 'B', 'C', 4);
// -> [ [ 1, 'A', 'B' ], [ 2, 'A', 'C' ], [ 1, 'B', 'C' ], [ 3, 'A', 'B' ],
//      [ 1, 'C', 'A' ], [ 2, 'C', 'B' ], [ 1, 'A', 'B' ], [ 4, 'A', 'C' ],
//      [ 1, 'B', 'C' ], [ 2, 'B', 'A' ], [ 1, 'C', 'A' ], [ 3, 'B', 'C' ],
//      [ 1, 'A', 'B' ], [ 2, 'A', 'C' ], [ 1, 'B', 'C' ] ]

plexho.lisp

(defun hanoi-ops (s tmp d n)
  (if (zerop n) '()
      (append (hanoi-ops s d tmp (- n 1))
              `((,n ,s ,d))
              (hanoi-ops tmp s d (- n 1)))))

(hanoi-ops 'A 'B 'C 4)
; -> ((1 A B) (2 A C) (1 B C) (3 A B) (1 C A) (2 C B) (1 A B) (4 A C)
;     (1 B C) (2 B A) (1 C A) (3 B C) (1 A B) (2 A C) (1 B C))

plexho.scm

(define (hanoi-ops s t d n)
  (if (zero? n) '()
      (append (hanoi-ops s d t (- n 1))
              `((,n ,s ,d))
              (hanoi-ops t s d (- n 1)))))

(hanoi-ops 'A 'B 'C 4)
; -> ((1 A B) (2 A C) (1 B C) (3 A B) (1 C A) (2 C B) (1 A B) (4 A C)
;     (1 B C) (2 B A) (1 C A) (3 B C) (1 A B) (2 A C) (1 B C))