80 lines
2.6 KiB
Clojure
80 lines
2.6 KiB
Clojure
(def n 5)
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(def m 4)
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(def start-position '(1 1))
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;; path - '((1 1) (4 2) (0 0))
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(def knight-moves '((2 1) (2 -1) (-2 1) (-2 -1) (1 2) (1 -2) (-1 2) (-1 -2)))
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(defn check-pos? (p) (and (<= 1 (car p) n) (<= 1 (car (cdr p)) m)))
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(def all-cells
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(concat (map (lambda (r)
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(map (lambda (c)
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(list r c))
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(range 1 (+ 1 m))))
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(range 1 (+ 1 n)))))
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(def all-moves (concat (map (lambda (cell)
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(filter (lambda (step) (check-pos? (car step)))
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(map (lambda (delta-move) (list (zip-with + cell delta-move) cell))
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knight-moves)))
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all-cells)))
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(defn steps-set-gen ()
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(eval (cons do (map (lambda (step) (list def (symbol (++ step)) false)) all-moves)))
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(defn add (x) (eval (list set! (symbol (++ x)) true)))
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(defn has? (x) (eval (symbol (++ x))))
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(defn remove (x) (eval (list set! (symbol (++ x)) false)))
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(lambda (cmd) (eval cmd))
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)
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(def steps-set (steps-set-gen))
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(defn check-step? (step path) (not ((steps-set 'has?) step)))
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(defmacro -= (x v) (set! x (- x v)))
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(defmacro += (x v) (set! x (+ x v)))
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(defn cells-multiset-gen ()
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(eval (cons do (map (lambda (cell) (list def (symbol (++ cell)) 0)) all-cells)))
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(def distinct 0)
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(defn add (x) (do
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(def name (symbol (++ x)))
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(when (= (eval name) 0) (+= distinct 1))
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(eval (list += name 1))))
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(defn remove (x) (do
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(def name (symbol (++ x)))
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(when (= (eval name) 1) (-= distinct 1))
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(eval (list -= name 1))))
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;; (defn distinct () xxx)
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(lambda (cmd) (eval cmd))
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)
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(def cells-multiset (cells-multiset-gen))
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(defn dfs (path)
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;; (def current-position (car path))
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;; (print path)
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(if (and (= (car path) start-position) (= (cells-multiset 'distinct) (* n m)))
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path
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(reduce (lambda (acc, x)
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(if (!= acc false) acc
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(do
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(def new-pos (zip-with + x (car path)))
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(def step (list new-pos (car path)))
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(if (and (check-pos? new-pos) (check-step? step path))
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(do ((steps-set 'add) step)
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((cells-multiset 'add) new-pos)
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(def res (dfs (cons new-pos path)))
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((steps-set 'remove) step)
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((cells-multiset 'remove) new-pos)
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res
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)
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false))))
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false knight-moves))
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)
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