Solution to "All Your Base" Google Codejam contest in Clojure http://code.google.com/codejam/contest/189252/dashboard#s=p0

all_your_base.clj

(ns jam.all-your-base
  (:require [clojure.math.numeric-tower :as math]))

(def in (rest (clojure.string/split (slurp "A-large-practice.in") #"\n")))

(defn p [x y]
  (math/expt x y))

(defn next-index [x]
  (cond
   (= x 0) 1
   (= x 1) 0
   :else x))

(defn solve [q]
  (let [alphabet (into (sorted-set) (distinct q))
        base (max 2 (count alphabet))]
    (loop [left (seq q)
           position 0
           result (bigint 0)
           code {}]
      (if (nil? (first left))
        result
        (let [x (first left)
              new-val (if (contains? code x)
                        (code x)
                        (next-index (count code)))]
            (recur (rest left) (inc position)
                   (+ result (* (p base (dec (count left))) new-val))
                   (assoc code x new-val)))))))

(defn write-solve [i x]
  (format "Case #%d: %d" (inc i) (biginteger (solve x))))

(spit "answerlarge.out2" (clojure.string/join "\n" (map-indexed write-solve in)))