Merge pull request #4944 from tylerw/tw/challenge-132

Challenge 132 in Clojure

8 files changed, 157 insertions, 14 deletions

diff --git a/challenge-132/tyler-wardhaugh/clojure/README.md b/challenge-132/tyler-wardhaugh/clojure/README.md
index 064e23e11f..74b8669aa3 100644
--- a/challenge-132/tyler-wardhaugh/clojure/README.md
+++ b/challenge-132/tyler-wardhaugh/clojure/README.md
@@ -1,7 +1,7 @@
-# tw.weekly.c130
+# tw.weekly.c132
 
 
-The Weekly Challenge - #130 - Tyler Wardhaugh
+The Weekly Challenge - #132 - Tyler Wardhaugh
 
 ## Usage
 
@@ -9,7 +9,7 @@ Clojure ([installation instructions](https://clojure.org/guides/getting_started#
 
 Run the project directly (shows default output from both tasks):
 
-    $ clojure -M -m tw.weekly.c130.core
+    $ clojure -M -m tw.weekly.c132.core
     # ... or ...
     $ bb run both
 
@@ -21,15 +21,13 @@ Run the project's tests (which are samples from the task descriptions):
 
 Run Task #1 with input
 
-    $ clojure -M -m tw.weekly.c130.t1 N
-    # ... or ...
-    $ bb run task-1 N
+    $ clojure -M -m tw.weekly.c132.t1 D
 
 Run Task #2 with input:
 
-    $ clojure -M -m tw.weekly.c130.t2 D S
+    $ clojure -M -m tw.weekly.c132.t2 H1 H2 I1 I2
     # ... or ...
-    $ bb run task-2 D S
+    $ bb run task-2 H1 H2 I1 I2
 
 View available tasks Babashka can run:
 
diff --git a/challenge-132/tyler-wardhaugh/clojure/bb.edn b/challenge-132/tyler-wardhaugh/clojure/bb.edn
index 4cd11817b8..a0e8b96a48 100644
--- a/challenge-132/tyler-wardhaugh/clojure/bb.edn
+++ b/challenge-132/tyler-wardhaugh/clojure/bb.edn
@@ -63,7 +63,9 @@
           :task (run-task :t1 *command-line-args*)}
 
   task-1-bb {:doc "Run Task 1 (via Babashka)"
-             :task (run-task-bb :t1 *command-line-args*)}
+             :task (binding [*out* *err*]
+                     (println "error: can't run Task 1 via Babashka because it depends on some incompatible libraries.")
+                     (System/exit 1))}
 
   task-2 {:doc "Run Task 2 (via clojure)"
           :task (run-task :t2 *command-line-args*)}
diff --git a/challenge-132/tyler-wardhaugh/clojure/deps.edn b/challenge-132/tyler-wardhaugh/clojure/deps.edn
index 5b1400b27e..e821835450 100644
--- a/challenge-132/tyler-wardhaugh/clojure/deps.edn
+++ b/challenge-132/tyler-wardhaugh/clojure/deps.edn
@@ -1,5 +1,6 @@
 {:paths ["src" "resources"]
- :deps {org.clojure/clojure {:mvn/version "1.10.3"}}
+ :deps {org.clojure/clojure {:mvn/version "1.10.3"}
+        clojure.java-time/clojure.java-time {:mvn/version "0.3.3"}}
  :aliases
  {:test {:extra-paths ["test"]
          :extra-deps {org.clojure/test.check {:mvn/version "1.1.0"}
diff --git a/challenge-132/tyler-wardhaugh/clojure/pom.xml b/challenge-132/tyler-wardhaugh/clojure/pom.xml
index b1039ce744..ca7a3f1f2a 100644
--- a/challenge-132/tyler-wardhaugh/clojure/pom.xml
+++ b/challenge-132/tyler-wardhaugh/clojure/pom.xml
@@ -2,11 +2,11 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>tw.weekly</groupId>
-  <artifactId>tw.weekly.c131</artifactId>
+  <artifactId>tw.weekly.c132</artifactId>
   <version>0.1.0-SNAPSHOT</version>
-  <name>tw.weekly.c131</name>
-  <description>Challenge #131</description>
-  <url>https://github.com/tw.weekly/tw.weekly.c131</url>
+  <name>tw.weekly.c132</name>
+  <description>Challenge #132</description>
+  <url>https://github.com/tw.weekly/tw.weekly.c132</url>
   <licenses>
     <license>
       <name>Eclipse Public License</name>
@@ -24,6 +24,11 @@
       <artifactId>clojure</artifactId>
       <version>1.10.3</version>
     </dependency>
+    <dependency>
+      <groupId>clojure.java-time</groupId>
+      <artifactId>clojure.java-time</artifactId>
+      <version>0.3.3</version>
+    </dependency>
   </dependencies>
   <build>
     <sourceDirectory>src</sourceDirectory>
diff --git a/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/core.clj b/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/core.clj
new file mode 100644
index 0000000000..4115f99d9b
--- /dev/null
+++ b/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/core.clj
@@ -0,0 +1,12 @@
+(ns tw.weekly.c132.core
+  (:require [tw.weekly.c132.t1 :as t1])
+  (:require [tw.weekly.c132.t2 :as t2])
+  (:gen-class))
+
+(defn -main
+  "Run all tasks"
+  [& _]
+  (println "Task #1:")
+  (t1/-main)
+  (println "\nTask #2:")
+  (t2/-main))
diff --git a/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/t1.clj b/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/t1.clj
new file mode 100644
index 0000000000..b24255c143
--- /dev/null
+++ b/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/t1.clj
@@ -0,0 +1,35 @@
+(ns tw.weekly.c132.t1
+  (:require [java-time :as j]
+            [clojure.pprint :refer [cl-format]]))
+
+;;;
+; Task description for TASK #1 › Mirror Dates
+;;;
+(def DEFAULT-TODAY "2021/09/22")
+(def DEFAULT-INPUT ["2021/09/18" DEFAULT-TODAY])
+(def DATE-FORMAT "yyyy/MM/dd")
+
+(defn parse-date
+  [s]
+  (j/local-date DATE-FORMAT s))
+
+(defn format-date
+  [d]
+  (-> (j/formatter DATE-FORMAT)
+      (j/format d)))
+
+(defn mirror-date
+  [origin today]
+  (let [delta (j/time-between :days origin today)
+        before (j/minus origin (j/days delta))
+        after (j/plus today (j/days delta))]
+    (list before after)))
+
+(defn -main
+  "Run Task 1 with a given input N, defaulting to the first example from the
+  task description."
+  [& args]
+  (let [[origin today] (map parse-date (or args DEFAULT-INPUT))]
+    (->> (mirror-date origin today)
+         (map format-date)
+         (cl-format true "~{~a~^, ~}~%"))))
diff --git a/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/t2.clj b/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/t2.clj
new file mode 100644
index 0000000000..0f0930b838
--- /dev/null
+++ b/challenge-132/tyler-wardhaugh/clojure/src/tw/weekly/c132/t2.clj
@@ -0,0 +1,62 @@
+(ns tw.weekly.c132.t2
+  (:require [clojure.edn :as edn]
+            [clojure.pprint :refer [cl-format]]))
+
+;;;
+; Task description for TASK #2, Hash Join
+;;;
+(def MAXSIZE "The maximum number of build relations to process at one time." 3)
+(def DEFAULT-INPUT
+  [[[20, "Alex"  ]
+    [28, "Joe"   ]
+    [38, "Mike"  ]
+    [18, "Alex"  ]
+    [25, "David" ]
+    [18, "Simon" ]]
+   [["Alex", "Stewart"]
+    ["Joe",  "Root"   ]
+    ["Mike", "Gatting"]
+    ["Joe",  "Blog"   ]
+    ["Alex", "Jones"  ]
+    ["Simon","Duane"  ]]
+   1
+   0])
+
+(defn butnth
+  "Returns all values except the one at index."
+  [coll index]
+  (keep-indexed (fn [i v] (when (not= i index) v)) coll))
+
+;;; Classic Hash Join
+;; Algorithm description:
+;   https://en.wikipedia.org/wiki/Hash_join#Classic_hash_join
+;; Notes:
+;   - We proactively batch the smaller relation (build) into MAXSIZE chunks to
+;     ensure it can fit into memory.
+;   - Order of output relation is not guaranteed.
+;;;
+(defn hash-join
+  [a b a-index b-index]
+  (let [[build build-index probe probe-index]
+        (if (<= (count a) (count b))
+          [a a-index b b-index]
+          [b b-index a a-index])]
+    (-> (comp
+          (partition-all MAXSIZE)
+          (map (fn [batch] (group-by #(nth % build-index) batch)))
+          (mapcat
+            (fn [build-map]
+              (keep (fn [row]
+                      (when-let [ks (build-map (nth row probe-index))]
+                        (map #(concat % (butnth row probe-index)) ks)))
+                    probe)))
+          cat)
+        (sequence build))))
+
+(defn -main
+  "Run Task 1 with a given input H1, H2, I1, and I2, defaulting to the first
+  example from the task description."
+  [& args]
+  (let [[H1 H2 I1 I2] (or (some->> args (map edn/read-string)) DEFAULT-INPUT)]
+    (->> (hash-join H1 H2 I1 I2)
+         (cl-format true "~:{~a, ~s, ~s~%~}"))))
diff --git a/challenge-132/tyler-wardhaugh/clojure/test/tw/weekly/c132_test.clj b/challenge-132/tyler-wardhaugh/clojure/test/tw/weekly/c132_test.clj
new file mode 100644
index 0000000000..00edee2c66
--- /dev/null
+++ b/challenge-132/tyler-wardhaugh/clojure/test/tw/weekly/c132_test.clj
@@ -0,0 +1,28 @@
+(ns tw.weekly.c132-test
+  (:require [clojure.test :refer [deftest is testing]]
+            [tw.weekly.c132.t1 :as t1]
+            [tw.weekly.c132.t2 :as t2]))
+
+(def today (t1/parse-date t1/DEFAULT-TODAY))
+
+(deftest task-1
+  (testing "Task 1, Mirror Dates"
+    (let [today (t1/parse-date t1/DEFAULT-TODAY)]
+      (is (= (map t1/parse-date ["2021/09/14" "2021/09/26"])
+             (t1/mirror-date (t1/parse-date "2021/09/18") today)))
+      (is (= (map t1/parse-date ["1929/10/27" "2067/09/05"])
+             (t1/mirror-date (t1/parse-date "1975/10/10") today)))
+      (is (= (map t1/parse-date ["1912/07/08" "2076/04/30"])
+             (t1/mirror-date (t1/parse-date "1967/02/14") today))))))
+
+(deftest task-2
+  (testing "Task 2, Hash Join"
+    (is  (= (set '((20 "Alex" "Stewart")
+                   (18 "Alex" "Stewart")
+                   (28 "Joe" "Root")
+                   (38 "Mike" "Gatting")
+                   (28 "Joe" "Blog")
+                   (20 "Alex" "Jones")
+                   (18 "Alex" "Jones")
+                   (18 "Simon" "Duane")))
+            (set (apply t2/hash-join t2/DEFAULT-INPUT))))))