solved pied piper problem - first crack

Author: Ramesh Sangaraju

src/clojure_practice/random/pied_piper.clj

@@ -0,0 +1,145 @@
+(ns clojure-practice.random.pied-piper
+  (:require [clojure.string :as str]))
+
+(comment
+
+  "The Pied Piper has been enlisted to play his magical tune and coax all the rats out of town.
+
+  But some of the rats are deaf and are going the wrong way!
+
+  How many deaf rats are there?
+
+  Legend
+
+  P = The Pied Piper
+  O ~ = Rat going left
+  ~O = Rat going right
+  Example
+
+  ex1 ~O ~O ~O ~O P has 0 deaf rats
+  ex2 P O ~ O ~ ~O O ~ has 1 deaf rat
+  ex3 ~O ~O ~O ~OP ~O ~OO~ has 2 deaf rats"
+
+  )
+
+(defn rats-count
+  [rats-str]
+  (loop [rats       (partition 2 rats-str)
+         left-rats  0
+         right-rats 0]
+    ; (println {:left-rats  left-rats :right-rats right-rats})
+    (if rats
+      (let [rat (first rats)]
+        (recur (next rats)
+               (if (= (last rat) \~)
+                 (inc left-rats)
+                 left-rats)
+               (if (= (first rat) \~)
+                 (inc right-rats)
+                 right-rats)))
+      {:left-rats  left-rats
+       :right-rats right-rats})))
+
+#_(defn where-is-piper?
+    [input-str]
+    (cond (= (first input-str) \P) :left
+          (= (last input-str) \P) :right
+          :else :random))
+
+#_(defn deaf-rats-count*
+    [rats-count piper-direction]
+    (cond (= piper-direction :left) (-> rats-count
+                                        :right-rats)
+          (= piper-direction :right) (-> rats-count
+                                         :left-rats)))
+(defn deaf-rats-on-left-of-piper
+  [rats-count]
+  (-> rats-count
+      :left-rats))
+
+(defn deaf-rats-on-right-of-piper
+  [rats-count]
+  (-> rats-count
+      :right-rats))
+
+
+(defn deaf-rats-count
+  [input]
+  (let [input-str-with-no-spaces     (str/replace input
+                                                  " "
+                                                  "")
+        rats-left-and-right-of-piper (str/split input-str-with-no-spaces
+                                                #"P"
+                                                -1)
+        ;_                               (println "rats-on-left-and-right-of-piper: " rats-on-left-and-right-of-piper)
+        [rats-count-left-of-piper rats-count-right-of-piper] (mapv rats-count
+                                                                   rats-left-and-right-of-piper)
+        ;_                               (println (str rats-count-left-of-piper " P " rats-count-right-of-piper))
+        ]
+    (+ (deaf-rats-on-left-of-piper rats-count-left-of-piper)
+       (deaf-rats-on-right-of-piper rats-count-right-of-piper))))
+
+
+;;REPL execution block
+(comment
+  (str/split "~O ~O ~O ~O P" #"P" -1)
+  #_=> ["~O ~O ~O ~O " ""]
+  (str/split "~O ~O ~O ~OP ~O ~OO~" #"P")
+  #_=> ["~O ~O ~O ~O" " ~O ~OO~"]
+
+  (str/replace "~O ~O ~O ~OP ~O ~OO~"
+               " "
+               "")
+  #_=> "~O~O~O~OP~O~OO~"
+
+  (str/replace "~O ~O ~O ~O P"
+               " "
+               "")
+  #_=> "~O~O~O~OP"
+
+  (str/replace "P O ~ O ~ ~O O ~"
+               " "
+               "")
+  #_=> "PO~O~~OO~"
+
+  ;(where-is-piper? "~O~O~O~OP~O~OO~")
+  ;#_=> :random
+  ;
+  ;(where-is-piper? "~O~O~O~OP")
+  ;#_=> :right
+  ;
+  ;(where-is-piper? "PO~O~~OO~")
+  ;#_=> :left
+
+  (partition 2 "~O~O~O~O")
+  #_=> ((\~ \O) (\~ \O) (\~ \O) (\~ \O))
+
+  (rats-count "~O~O~O~O")
+  #_=> {:left-rats 0, :right-rats 4}
+
+  (rats-count "~O~O~O~O~O~OO~")
+  #_=> {:left-rats 1, :right-rats 6}
+
+  (rats-count "O~O~~OO~")
+  #_=> {:left-rats 3, :right-rats 1}
+
+  (deaf-rats-on-right-of-piper {:left-rats 3, :right-rats 1})
+  #_=> 1
+
+  (deaf-rats-on-left-of-piper {:left-rats 0, :right-rats 0})
+  #_=> 0
+
+  (deaf-rats-count "PO~O~~OO~")
+  #_=> 1
+
+  (deaf-rats-count "~O ~O ~O ~O P")
+  #_=> 0
+
+  (deaf-rats-count "~O ~O ~O ~OP ~O ~OO~")
+  #_=> 2
+
+  (deaf-rats-count "P")
+  #_=> 0
+
+
+  )