Mercurial > coderloop
comparison src/reverse_seq.clj @ 0:307a81e46071 tip
initial committ
| author | Robert McIntyre <rlm@mit.edu> |
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| date | Tue, 18 Oct 2011 01:17:49 -0700 |
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| children |
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| -1:000000000000 | 0:307a81e46071 |
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| 1 (ns coderloop.reverse-seq | |
| 2 (:use [clojure.contrib | |
| 3 [duck-streams :only [file-str read-lines]] | |
| 4 [str-utils :only [re-split]]]) | |
| 5 (:use rlm.shell-inspect) | |
| 6 (:use [clojure [string :only [trim]]])) | |
| 7 | |
| 8 (def c (file-str "/home/r/coderloop-test/reversesequence-c.in")) | |
| 9 (def a (file-str "/home/r/coderloop-test/reversesequence-a.in")) | |
| 10 (def b (file-str "/home/r/coderloop-test/reversesequence-b.in")) | |
| 11 | |
| 12 (defn test-trace-map [] | |
| 13 (= [:a :b :c :d :e] | |
| 14 (trace-map {:a :b :d :e :c :d :b :c}))) | |
| 15 | |
| 16 | |
| 17 (defn read-name-map | |
| 18 "takes a file of pairs of names and returns a map from the first | |
| 19 element in those pairs to the second element in the pairs." | |
| 20 [#^java.io.File file] | |
| 21 (let [pairs (map #(re-split #"\W+" (trim %)) (read-lines file))] | |
| 22 (zipmap (map first pairs) (map second pairs)))) | |
| 23 | |
| 24 (defn start-linked-map | |
| 25 "takes a map-representing-a-list and finds the beginning of that list" | |
| 26 [m] | |
| 27 (first (remove (set (vals m)) (keys m)))) | |
| 28 | |
| 29 (defn trace-map | |
| 30 "chains through a map-representing-a-list, building a list along the way." | |
| 31 [m] | |
| 32 (loop [index (start-linked-map m) | |
| 33 chain (vector index)] | |
| 34 (let [new-index (get m index ::sentinel)] | |
| 35 (if (= new-index ::sentinel) | |
| 36 chain | |
| 37 (recur new-index (conj chain new-index)))))) | |
| 38 | |
| 39 | |
| 40 | |
| 41 (if (command-line?) | |
| 42 (dorun | |
| 43 (map println (reverse (trace-map (read-name-map (file-str (first *command-line-args*)))))))) |