Add secret-handshake exercise (#150)

config.json

@@ -585,6 +585,18 @@
         ],
         "difficulty": 2
       },
+      {
+        "slug": "secret-handshake",
+        "name": "Secret Handshake",
+        "uuid": "e367eaee-7ad3-46bf-86cb-922b797f8829",
+        "practices": [],
+        "prerequisites": [
+          "numbers",
+          "vectors",
+          "strings"
+        ],
+        "difficulty": 2
+      },
       {
         "slug": "rotational-cipher",
         "name": "Rotational Cipher",

exercises/practice/secret-handshake/.docs/instructions.md

@@ -0,0 +1,48 @@
+# Instructions
+
+Your task is to convert a number between 1 and 31 to a sequence of actions in the secret handshake.
+
+The sequence of actions is chosen by looking at the rightmost five digits of the number once it's been converted to binary.
+Start at the right-most digit and move left.
+
+The actions for each number place are:
+
+```plaintext
+00001 = wink
+00010 = double blink
+00100 = close your eyes
+01000 = jump
+10000 = Reverse the order of the operations in the secret handshake.
+```
+
+Let's use the number `9` as an example:
+
+- 9 in binary is `1001`.
+- The digit that is farthest to the right is 1, so the first action is `wink`.
+- Going left, the next digit is 0, so there is no double-blink.
+- Going left again, the next digit is 0, so you leave your eyes open.
+- Going left again, the next digit is 1, so you jump.
+
+That was the last digit, so the final code is:
+
+```plaintext
+wink, jump
+```
+
+Given the number 26, which is `11010` in binary, we get the following actions:
+
+- double blink
+- jump
+- reverse actions
+
+The secret handshake for 26 is therefore:
+
+```plaintext
+jump, double blink
+```
+
+~~~~exercism/note
+If you aren't sure what binary is or how it works, check out [this binary tutorial][intro-to-binary].
+
+[intro-to-binary]: https://medium.com/basecs/bits-bytes-building-with-binary-13cb4289aafa
+~~~~

exercises/practice/secret-handshake/.docs/introduction.md

@@ -0,0 +1,7 @@
+# Introduction
+
+You are starting a secret coding club with some friends and friends-of-friends.
+Not everyone knows each other, so you and your friends have decided to create a secret handshake that you can use to recognize that someone is a member.
+You don't want anyone who isn't in the know to be able to crack the code.
+
+You've designed the code so that one person says a number between 1 and 31, and the other person turns it into a series of actions.

exercises/practice/secret-handshake/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "ErikSchierboom"
+  ],
+  "files": {
+    "solution": [
+      "src/secret_handshake.cljs"
+    ],
+    "test": [
+      "test/secret_handshake_test.cljs"
+    ],
+    "example": [
+      ".meta/src/example.cljs"
+    ]
+  },
+  "blurb": "Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.",
+  "source": "Bert, in Mary Poppins",
+  "source_url": "https://www.imdb.com/title/tt0058331/quotes/qt0437047"
+}

exercises/practice/secret-handshake/.meta/src/example.cljs

@@ -0,0 +1,16 @@
+(ns secret-handshake)
+
+(def coded-commands
+  {
+     0 #(conj % "wink")
+     1 #(conj % "double blink")
+     2 #(conj % "close your eyes")
+     3 #(conj % "jump")
+     4 reverse
+   })
+
+(defn- update-commands [code commands [command-nth-bit command]]
+  (if (bit-test code command-nth-bit) (command commands) commands))
+
+(defn commands [code]
+  (reduce (partial update-commands code) [] coded-commands))

exercises/practice/secret-handshake/.meta/tests.toml

@@ -0,0 +1,36 @@
+# This is an auto-generated file. Regular comments will be removed when this
+# file is regenerated. Regenerating will not touch any manually added keys,
+# so comments can be added in a "comment" key.
+
+[b8496fbd-6778-468c-8054-648d03c4bb23]
+description = "wink for 1"
+
+[83ec6c58-81a9-4fd1-bfaf-0160514fc0e3]
+description = "double blink for 10"
+
+[0e20e466-3519-4134-8082-5639d85fef71]
+description = "close your eyes for 100"
+
+[b339ddbb-88b7-4b7d-9b19-4134030d9ac0]
+description = "jump for 1000"
+
+[40499fb4-e60c-43d7-8b98-0de3ca44e0eb]
+description = "combine two actions"
+
+[9730cdd5-ef27-494b-afd3-5c91ad6c3d9d]
+description = "reverse two actions"
+
+[0b828205-51ca-45cd-90d5-f2506013f25f]
+description = "reversing one action gives the same action"
+
+[9949e2ac-6c9c-4330-b685-2089ab28b05f]
+description = "reversing no actions still gives no actions"
+
+[23fdca98-676b-4848-970d-cfed7be39f81]
+description = "all possible actions"
+
+[ae8fe006-d910-4d6f-be00-54b7c3799e79]
+description = "reverse all possible actions"
+
+[3d36da37-b31f-4cdb-a396-d93a2ee1c4a5]
+description = "do nothing for zero"

exercises/practice/secret-handshake/deps.edn

@@ -0,0 +1,10 @@
+{:deps
+ {org.clojure/clojure {:mvn/version "1.10.1"}
+  org.clojure/clojurescript {:mvn/version "1.10.773"}}
+
+ :aliases
+ {:test
+  {:extra-paths ["test"]
+   :extra-deps
+   {olical/cljs-test-runner {:mvn/version "3.8.0"}}
+   :main-opts ["-m" "cljs-test-runner.main"]}}}

exercises/practice/secret-handshake/src/secret_handshake.cljs

@@ -0,0 +1,5 @@
+(ns secret-handshake)
+
+(defn commands [] ;; <- arglist goes here
+      ;; your code goes here
+)

exercises/practice/secret-handshake/test/secret_handshake_test.cljs

@@ -0,0 +1,55 @@
+(ns secret-handshake-test
+  (:require [clojure.test :refer [deftest testing is]]
+            secret-handshake))
+
+(deftest wink
+  (testing "a wink is returned for binary 1"
+    (is (= ["wink"] (secret-handshake/commands 1)))))
+
+(deftest double-blink
+  (testing "a double blink is returned for a binary 10"
+    (is (= ["double blink"] (secret-handshake/commands 2)))))
+
+(deftest close-your-eyes
+  (testing "a close your eyes is returned for a binary 100"
+    (is (= ["close your eyes"] (secret-handshake/commands 4)))))
+
+(deftest jump
+  (testing "a jump is returned for a binary 1000"
+    (is (= ["jump"] (secret-handshake/commands 8)))))
+
+(deftest two-actions
+  (testing "commands returns multiple actions"
+    (is (= ["wink" "double blink"] (secret-handshake/commands 3)))))
+
+(deftest reversing
+  (testing "giving a binary 10000 reverses actions"
+    (is (= ["double blink" "wink"] (secret-handshake/commands 19)))))
+
+(deftest reversing-one-action
+  (testing "reversing one action returns the same action"
+    (is (= ["jump"] (secret-handshake/commands 24)))))
+
+(deftest reverse-nothing
+  (testing "reversing nothing still gives nothing"
+    (is (= [] (secret-handshake/commands 16)))))
+
+(deftest all-actions
+  (testing "all actions together"
+    (is (=
+         ["wink" "double blink" "close your eyes" "jump"]
+         (secret-handshake/commands 15)))))
+
+(deftest reverse-all-actions
+  (testing "reversing all actions together"
+    (is (=
+         ["jump" "close your eyes" "double blink" "wink"]
+         (secret-handshake/commands 31)))))
+
+(deftest nothing
+  (testing "do nothing for 0"
+    (is (= [] (secret-handshake/commands 0)))))
+
+(deftest lower-5-bits-zero
+  (testing "do nothing for high numbers if lower 5 bits not set"
+    (is (= [] (secret-handshake/commands 32)))))