The Clojure Program To solve N Queens Problem

The Clojure Program To solve N Queens Problem

The following program is about solving N-Queens problem (http://en.wikipedia.org/wiki/Eight_queens_puzzle) by Clojure. If you have the better solution in Clojure or Haskell, welcome to provide your solution.
(ns queens)

(defn conflictInRow? [queens newqueen]

  (some #(= newqueen %) queens)

)

(defn conflictInDia? [queens newqueen]

  (let [dia (count queens) 

        n1 (fn [queen] (Math/abs (- dia (.indexOf queens queen))))

        n2 (fn [queen] (Math/abs (- newqueen queen)))]

    (some #(= (n1 %) (n2 %)) queens)

   )

 )

(defn conflict? [queens newqueen]

  (or (conflictInRow? queens newqueen) (conflictInDia? queens newqueen))

 )

(def cnt (atom 0))

(defn put-queens [queens newqueen boardSize ]

  (if (= (count queens) boardSize)  

    (do

      (println queens)

      (reset! cnt (inc @cnt))

    )

    (do 

      ;(println queens)

      (if (> newqueen boardSize)

     

           (if (and (= (peek queens) boardSize) (= (count queens) 1))

               (throw (Exception. (str "That's all " @cnt)))

               (recur (pop queens) (inc (peek queens)) boardSize )

           )

     

        (if (conflict? queens newqueen)

            

             (recur queens (inc newqueen) boardSize )

             

          (do

             (put-queens (conj queens newqueen) 1 boardSize )

             (recur queens (inc newqueen) boardSize )

           )

        )

       )

      )

    )

    

)

(defn queens [boardSize] 

    (put-queens [] 1 boardSize)

 )


Chao Cai (蔡超）

Sr. Software Dev Engineer 
Amazon.com