Task #1: add more tests and fix the bugs uncovered

There were two problems uncovered by the tests, which include one test
that requires using a prime twice (6 = 3 + 3), one that is a prime (11),
and one that requires 3 terms (51 = 43 + 5 + 3 or 51 = 47 +2 + 2).

In find-min-primes-to-sum, I had the arguments to (conj) in the wrong
order for the case of requiring 3 terms.

In find-min-primes-to-sum-brute-force, I was not checking possibilities
involving the same primes twice, which I fixed by replacing
(combo/partitions) with (combo/selections) for both 2 and 3 terms.

2 files changed, 20 insertions, 15 deletions

diff --git a/challenge-076/tyler-wardhaugh/clojure/src/tw/weekly/ch_1.clj b/challenge-076/tyler-wardhaugh/clojure/src/tw/weekly/ch_1.clj
index 300b89c7ff..7e6fb06990 100644
--- a/challenge-076/tyler-wardhaugh/clojure/src/tw/weekly/ch_1.clj
+++ b/challenge-076/tyler-wardhaugh/clojure/src/tw/weekly/ch_1.clj
@@ -7,14 +7,15 @@
 (defn find-min-primes-to-sum-brute-force
   "Find the minimum number of prime numbers required, whose summation gives you the argument provided, by brute force."
   [n]
-  (if (p/prime? n) [n]
-    (as-> n x
-      (p/take-below x)
-      (combo/partitions x :min 2 :max 3)
-      (mapcat identity x)
-      (filter #(= n (reduce + %)) x)
-      (sort-by count x)
-      (first x))))
+  (if (p/prime? n)
+    [n]
+    (->> n
+      p/take-below
+      ((juxt #(combo/selections % 2) #(combo/selections % 3)))
+      (apply concat)
+      (filter #(= n (reduce + %)))
+      (sort-by count)
+      first)))
 
 ; basis for algorithm:
 ;   https://stackoverflow.com/a/35756072
@@ -26,12 +27,12 @@
     (p/prime? n) [n]
     (even? n) (let [f (juxt #(- n %) identity)] (->> (p/primes) (filter #(p/prime? (- n %))) first f))
     (and (odd? n) (p/prime? (- n 2))) [2 (- n 2)]
-    :else (conj 3 (find-min-primes-to-sum (- n 3)))))
+    :else (conj (find-min-primes-to-sum (- n 3)) 3)))
 
 (defn -main
   "Run Task 1 with a number N, defaulting to the number given in the task example, 9."
   [& args]
-    (let [N (or (some-> args first edn/read-string) 9)]
-    (let [solution (find-min-primes-to-sum N)]
-      (printf "%d prime number(s) are the minimum number required to sum to %d.\n" (count solution) N)
-      (println solution))))
+  (let [N (or (some-> args first edn/read-string) 9)
+        solution (find-min-primes-to-sum N)]
+    (printf "%d prime number(s) are the minimum number required to sum to %d:\n" (count solution) N)
+    (printf "%d = %s" N (apply str (interpose " + " solution)))))
diff --git a/challenge-076/tyler-wardhaugh/clojure/test/tw/weekly/c76_test.clj b/challenge-076/tyler-wardhaugh/clojure/test/tw/weekly/c76_test.clj
index 003ce81591..d6f01cb433 100644
--- a/challenge-076/tyler-wardhaugh/clojure/test/tw/weekly/c76_test.clj
+++ b/challenge-076/tyler-wardhaugh/clojure/test/tw/weekly/c76_test.clj
@@ -6,8 +6,12 @@
 
 (deftest ch-1
   (testing "Task 1"
-    (is (= 2 (count (find-min-primes-to-sum 9)) (count (find-min-primes-to-sum-brute-force 9))))
-    (is (= 2 (count (find-min-primes-to-sum 34)) (count (find-min-primes-to-sum-brute-force 34))))))
+    (let [n-and-results [[6 2] [9 2] [11 1] [12 2] [51 3]]
+          fns (juxt second (comp count find-min-primes-to-sum first) (comp count find-min-primes-to-sum-brute-force first))
+          results (->> n-and-results
+                       (map fns)
+                       (map #(is (apply = %))))]
+      (dorun results))))
 
 (deftest ch-2
   (testing "Task 2"