Add food-chain exercise (#785) (#782)

config.json

@@ -1290,6 +1290,18 @@
           "transforming"
         ]
       },
+      {
+        "slug": "knapsack",
+        "name": "Knapsack",
+        "uuid": "f1827715-0e86-42f2-b07d-4d70e8c2e043",
+        "practices": [],
+        "prerequisites": [
+          "numbers",
+          "vectors",
+          "conditionals"
+        ],
+        "difficulty": 5
+      },
       {
         "slug": "luhn",
         "name": "Luhn",

exercises/practice/knapsack/.docs/instructions.md

@@ -0,0 +1,25 @@
+# Instructions
+
+Your task is to determine which items to take so that the total value of her selection is maximized, taking into account the knapsack's carrying capacity.
+
+Items will be represented as a list of items.
+Each item will have a weight and value.
+All values given will be strictly positive.
+Lhakpa can take only one of each item.
+
+For example:
+
+```text
+Items: [
+  { "weight": 5, "value": 10 },
+  { "weight": 4, "value": 40 },
+  { "weight": 6, "value": 30 },
+  { "weight": 4, "value": 50 }
+]
+
+Knapsack Maximum Weight: 10
+```
+
+For the above, the first item has weight 5 and value 10, the second item has weight 4 and value 40, and so on.
+In this example, Lhakpa should take the second and fourth item to maximize her value, which, in this case, is 90.
+She cannot get more than 90 as her knapsack has a weight limit of 10.

exercises/practice/knapsack/.docs/introduction.md

@@ -0,0 +1,10 @@
+# Introduction
+
+Lhakpa is a [Sherpa][sherpa] mountain guide and porter.
+After months of careful planning, the expedition Lhakpa works for is about to leave.
+She will be paid the value she carried to the base camp.
+
+In front of her are many items, each with a value and weight.
+Lhakpa would gladly take all of the items, but her knapsack can only hold so much weight.
+
+[sherpa]: https://en.wikipedia.org/wiki/Sherpa_people#Mountaineering

exercises/practice/knapsack/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "src/knapsack.clj"
+    ],
+    "test": [
+      "test/knapsack_test.clj"
+    ],
+    "example": [
+      ".meta/example.clj"
+    ]
+  },
+  "blurb": "Given a knapsack that can only carry a certain weight, determine which items to put in the knapsack in order to maximize their combined value.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Knapsack_problem"
+}

exercises/practice/knapsack/.meta/example.clj

@@ -0,0 +1,12 @@
+(ns knapsack)
+
+(defn maximum-value [maximum-weight items]
+  (if (empty? items)
+    0
+    (max
+     (if (<= (:weight (first items)) maximum-weight)
+       (+
+        (:value (first items))
+        (maximum-value (- maximum-weight (:weight (first items))) (rest items)))
+       0)
+     (maximum-value maximum-weight (rest items)))))

exercises/practice/knapsack/.meta/generator.clj

@@ -0,0 +1,11 @@
+(ns knapsack-generator
+  (:require [hbs.helper :refer [safe-str]]))
+
+(defn- update-item [item]
+  (safe-str (str item)))
+
+(defn- update-items [items]
+  (map update-item items))
+
+(defn update-test-case [test-case]
+  (update-in test-case [:input :items] update-items))

exercises/practice/knapsack/.meta/generator.tpl

@@ -0,0 +1,10 @@
+(ns knapsack-test
+  (:require [clojure.test :refer [deftest testing is]]
+            knapsack))
+
+{{#test_cases.maximumValue}}
+(deftest maximum-value_test_{{idx}}
+  (testing {{description}}
+    (is (= {{expected}} (knapsack/maximum-value {{input.maximumWeight}} [{{#input.items}}
+     {{.}}{{/input.items}}])))))
+{{/test_cases.maximumValue}}

exercises/practice/knapsack/.meta/tests.toml

@@ -0,0 +1,36 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[a4d7d2f0-ad8a-460c-86f3-88ba709d41a7]
+description = "no items"
+include = false
+
+[3993a824-c20e-493d-b3c9-ee8a7753ee59]
+description = "no items"
+reimplements = "a4d7d2f0-ad8a-460c-86f3-88ba709d41a7"
+
+[1d39e98c-6249-4a8b-912f-87cb12e506b0]
+description = "one item, too heavy"
+
+[833ea310-6323-44f2-9d27-a278740ffbd8]
+description = "five items (cannot be greedy by weight)"
+
+[277cdc52-f835-4c7d-872b-bff17bab2456]
+description = "five items (cannot be greedy by value)"
+
+[81d8e679-442b-4f7a-8a59-7278083916c9]
+description = "example knapsack"
+
+[f23a2449-d67c-4c26-bf3e-cde020f27ecc]
+description = "8 items"
+
+[7c682ae9-c385-4241-a197-d2fa02c81a11]
+description = "15 items"

exercises/practice/knapsack/deps.edn

@@ -0,0 +1,6 @@
+{:aliases {:test {:extra-paths ["test"]
+                 :extra-deps {io.github.cognitect-labs/test-runner 
+                              {:git/url "https://github.com/cognitect-labs/test-runner.git"
+                               :sha "705ad25bbf0228b1c38d0244a36001c2987d7337"}}
+                 :main-opts ["-m" "cognitect.test-runner"]
+                 :exec-fn cognitect.test-runner.api/test}}}

exercises/practice/knapsack/project.clj

@@ -0,0 +1,4 @@
+(defproject knapsack "0.1.0-SNAPSHOT"
+  :description "knapsack exercise."
+  :url "https://github.com/exercism/clojure/tree/main/exercises/practice/knapsack"
+  :dependencies [[org.clojure/clojure "1.11.1"]])

exercises/practice/knapsack/src/knapsack.clj

@@ -0,0 +1,7 @@
+(ns knapsack)
+
+(defn maximum-value
+  "Calculates the maximum value that can be packed."
+  [maximum-weight items]
+  ;; function body
+  )

exercises/practice/knapsack/test/knapsack_test.clj

@@ -0,0 +1,63 @@
+(ns knapsack-test
+  (:require [clojure.test :refer [deftest testing is]]
+            knapsack))
+
+(deftest maximum-value_test_1
+  (testing "no items"
+    (is (= 0 (knapsack/maximum-value 100 [])))))
+
+(deftest maximum-value_test_2
+  (testing "one item, too heavy"
+    (is (= 0 (knapsack/maximum-value 10 [{:weight 100, :value 1}])))))
+
+(deftest maximum-value_test_3
+  (testing "five items (cannot be greedy by weight)"
+    (is (= 21 (knapsack/maximum-value 10 [{:weight 2, :value 5}
+                                          {:weight 2, :value 5}
+                                          {:weight 2, :value 5}
+                                          {:weight 2, :value 5}
+                                          {:weight 10, :value 21}])))))
+
+(deftest maximum-value_test_4
+  (testing "five items (cannot be greedy by value)"
+    (is (= 80 (knapsack/maximum-value 10 [{:weight 2, :value 20}
+                                          {:weight 2, :value 20}
+                                          {:weight 2, :value 20}
+                                          {:weight 2, :value 20}
+                                          {:weight 10, :value 50}])))))
+
+(deftest maximum-value_test_5
+  (testing "example knapsack"
+    (is (= 90 (knapsack/maximum-value 10 [{:weight 5, :value 10}
+                                          {:weight 4, :value 40}
+                                          {:weight 6, :value 30}
+                                          {:weight 4, :value 50}])))))
+
+(deftest maximum-value_test_6
+  (testing "8 items"
+    (is (= 900 (knapsack/maximum-value 104 [{:weight 25, :value 350}
+                                            {:weight 35, :value 400}
+                                            {:weight 45, :value 450}
+                                            {:weight 5, :value 20}
+                                            {:weight 25, :value 70}
+                                            {:weight 3, :value 8}
+                                            {:weight 2, :value 5}
+                                            {:weight 2, :value 5}])))))
+
+(deftest maximum-value_test_7
+  (testing "15 items"
+    (is (= 1458 (knapsack/maximum-value 750 [{:weight 70, :value 135}
+                                             {:weight 73, :value 139}
+                                             {:weight 77, :value 149}
+                                             {:weight 80, :value 150}
+                                             {:weight 82, :value 156}
+                                             {:weight 87, :value 163}
+                                             {:weight 90, :value 173}
+                                             {:weight 94, :value 184}
+                                             {:weight 98, :value 192}
+                                             {:weight 106, :value 201}
+                                             {:weight 110, :value 210}
+                                             {:weight 113, :value 214}
+                                             {:weight 115, :value 221}
+                                             {:weight 118, :value 229}
+                                             {:weight 120, :value 240}])))))