Task 2

6 files changed, 66 insertions, 3 deletions

diff --git a/challenge-077/tyler-wardhaugh/clojure/deps.edn b/challenge-077/tyler-wardhaugh/clojure/deps.edn
index b5563f1d16..0d1fedb8bb 100644
--- a/challenge-077/tyler-wardhaugh/clojure/deps.edn
+++ b/challenge-077/tyler-wardhaugh/clojure/deps.edn
@@ -1,7 +1,8 @@
 {:paths ["src" "resources"]
  :deps {org.clojure/clojure {:mvn/version "1.10.1"}
         org.clojure/math.combinatorics {:mvn/version "0.1.6"}
-        net.mikera/core.matrix {:mvn/version "0.62.0"}}
+        net.mikera/core.matrix {:mvn/version "0.62.0"}
+        pjstadig/reducible-stream {:mvn/version "0.1.5"}}
  :aliases
  {:test {:extra-paths ["test"]
          :extra-deps {org.clojure/test.check {:mvn/version "1.0.0"}}}
diff --git a/challenge-077/tyler-wardhaugh/clojure/resources/matrix1.txt b/challenge-077/tyler-wardhaugh/clojure/resources/matrix1.txt
new file mode 100644
index 0000000000..f8beeb613f
--- /dev/null
+++ b/challenge-077/tyler-wardhaugh/clojure/resources/matrix1.txt
@@ -0,0 +1,3 @@
+O O X
+X O O
+X O O
diff --git a/challenge-077/tyler-wardhaugh/clojure/resources/matrix2.txt b/challenge-077/tyler-wardhaugh/clojure/resources/matrix2.txt
new file mode 100644
index 0000000000..d81104f1b2
--- /dev/null
+++ b/challenge-077/tyler-wardhaugh/clojure/resources/matrix2.txt
@@ -0,0 +1,4 @@
+O O X O
+X O O O
+X O O X
+O X O O
diff --git a/challenge-077/tyler-wardhaugh/clojure/src/tw/weekly/ch-2.clj b/challenge-077/tyler-wardhaugh/clojure/src/tw/weekly/ch-2.clj
new file mode 120000
index 0000000000..5a32e17ef9
--- /dev/null
+++ b/challenge-077/tyler-wardhaugh/clojure/src/tw/weekly/ch-2.clj
@@ -0,0 +1 @@
+ch_2.clj
\ No newline at end of file
diff --git a/challenge-077/tyler-wardhaugh/clojure/src/tw/weekly/ch_2.clj b/challenge-077/tyler-wardhaugh/clojure/src/tw/weekly/ch_2.clj
new file mode 100644
index 0000000000..6c6854eef1
--- /dev/null
+++ b/challenge-077/tyler-wardhaugh/clojure/src/tw/weekly/ch_2.clj
@@ -0,0 +1,50 @@
+(ns tw.weekly.ch-2
+  (:require [clojure.java.io :as io])
+  (:require [clojure.string :as str])
+  (:require [clojure.core.matrix :as mat])
+  (:require [pjstadig.reducible-stream :refer [decode-lines!]]))
+
+;;; Task description
+; TASK #2 › Lonely X
+; You are given m x n character matrix consists of O and X only.
+;
+; Write a script to count the total number of X surrounded by O only. Print 0 if none found.
+;;;
+
+(defn parse-matrix-file
+  "Parse matrix file and convert 'O's to 0s and 'X's to 1s. Return a multidimensional vector of ints."
+  [matrix-file]
+  (let [source (decode-lines! matrix-file)
+        xf (comp (map #(str/split % #"\s+")) (map #(replace {"O" 0, "X" 1} %)))]
+    (into [] xf source)))
+
+(defn extend-matrix
+  "Surround the matrix in a 'border' of 0s. That is, add rows before the first and after the last rows and add columns before the first and after the last columns."
+  [matrix]
+  (let [n (mat/dimension-count matrix 1)
+        blank-row (vec (repeat (+ n 2) 0))
+        step-1 (reduce (fn [mat v] (conj mat (vec (concat [0] v [0])))) [blank-row] matrix)]
+    (conj step-1 blank-row)))
+
+(defn find-lonelies
+  "Find lonely values in a matrix."
+  [matrix]
+  (let [[m n] (mat/shape matrix)
+        extended (extend-matrix matrix)
+        canonical-lonely [[0 0 0] [0 1 0] [0 0 0]]]
+    (for [x (range 1 (inc m))
+          y (range 1 (inc n))
+          :let [submat (mat/submatrix extended [[(- x 1) 3] [(- y 1) 3]])]
+          :when (mat/e= canonical-lonely submat)]
+      [x y])))
+
+(defn -main
+  "Run Task 2 with a matrix file, defaulting to the 'matrix1.txt' file under the resources directory."
+  [& args]
+  (let [matrix-file (or (some-> args first io/file) (io/resource "matrix1.txt"))
+        matrix (parse-matrix-file matrix-file)]
+    (if-let [lonlies (find-lonelies matrix)]
+      (do
+        (printf "%d\n\nCoordinates:\n============\n" (count lonlies))
+        (run! println lonlies))
+      (println "No lonely Xs in matrix."))))
diff --git a/challenge-077/tyler-wardhaugh/clojure/test/tw/weekly/c77_test.clj b/challenge-077/tyler-wardhaugh/clojure/test/tw/weekly/c77_test.clj
index 7ab39d517a..e417556210 100644
--- a/challenge-077/tyler-wardhaugh/clojure/test/tw/weekly/c77_test.clj
+++ b/challenge-077/tyler-wardhaugh/clojure/test/tw/weekly/c77_test.clj
@@ -2,7 +2,7 @@
   (:require [clojure.test :refer :all]
             [clojure.java.io :as io]
             [tw.weekly.ch-1 :refer [fibo-sum]]
-            [tw.weekly.ch-2 :refer []]))
+            [tw.weekly.ch-2 :refer [parse-matrix-file find-lonelies]]))
 
 (deftest ch-1
   (testing "Task 1"
@@ -11,4 +11,8 @@
 
 (deftest ch-2
   (testing "Task 2"
-    ))
+    (with-test
+      (defn f [filename]
+        (-> filename io/resource parse-matrix-file find-lonelies))
+      (is (= (f "matrix1.txt") [[1 3]]))
+      (is (= (f "matrix2.txt") [[1 3] [3 4]])))))