Merge pull request #125 from keiravillekode/largest-series-product

Add largest-series-product exercise

config.json

@@ -247,6 +247,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "largest-series-product",
+        "name": "Largest Series Product",
+        "uuid": "2534388c-96ef-45f7-a4e2-eb830dfb9c66",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "sieve",
         "name": "Sieve of Eratosthenes",

exercises/practice/largest-series-product/.docs/instructions.append.md

@@ -0,0 +1,9 @@
+# Instruction append
+
+If the input is invalid, return `-1`.
+
+## Reserved Memory
+
+The buffer for the input string uses bytes 64-319 of linear memory.
+
+The input string can be modified if desired.

exercises/practice/largest-series-product/.docs/instructions.md

@@ -0,0 +1,26 @@
+# Instructions
+
+Your task is to look for patterns in the long sequence of digits in the encrypted signal.
+
+The technique you're going to use here is called the largest series product.
+
+Let's define a few terms, first.
+
+- **input**: the sequence of digits that you need to analyze
+- **series**: a sequence of adjacent digits (those that are next to each other) that is contained within the input
+- **span**: how many digits long each series is
+- **product**: what you get when you multiply numbers together
+
+Let's work through an example, with the input `"63915"`.
+
+- To form a series, take adjacent digits in the original input.
+- If you are working with a span of `3`, there will be three possible series:
+  - `"639"`
+  - `"391"`
+  - `"915"`
+- Then we need to calculate the product of each series:
+  - The product of the series `"639"` is 162 (`6 × 3 × 9 = 162`)
+  - The product of the series `"391"` is 27 (`3 × 9 × 1 = 27`)
+  - The product of the series `"915"` is 45 (`9 × 1 × 5 = 45`)
+- 162 is bigger than both 27 and 45, so the largest series product of `"63915"` is from the series `"639"`.
+  So the answer is **162**.

exercises/practice/largest-series-product/.docs/introduction.md

@@ -0,0 +1,5 @@
+# Introduction
+
+You work for a government agency that has intercepted a series of encrypted communication signals from a group of bank robbers.
+The signals contain a long sequence of digits.
+Your team needs to use various digital signal processing techniques to analyze the signals and identify any patterns that may indicate the planning of a heist.

exercises/practice/largest-series-product/.eslintrc

@@ -0,0 +1,18 @@
+{
+  "root": true,
+  "extends": "@exercism/eslint-config-javascript",
+  "env": {
+    "jest": true
+  },
+  "overrides": [
+    {
+      "files": [
+        "*.spec.js"
+      ],
+      "excludedFiles": [
+        "custom.spec.js"
+      ],
+      "extends": "@exercism/eslint-config-javascript/maintainers"
+    }
+  ]
+}

exercises/practice/largest-series-product/.meta/config.json

@@ -0,0 +1,28 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "largest-series-product.wat"
+    ],
+    "test": [
+      "largest-series-product.spec.js"
+    ],
+    "example": [
+      ".meta/proof.ci.wat"
+    ],
+    "invalidator": [
+      "package.json"
+    ]
+  },
+  "blurb": "Given a string of digits, calculate the largest product for a contiguous substring of digits of length n.",
+  "source": "A variation on Problem 8 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=8",
+  "custom": {
+    "version.tests.compatibility": "jest-27",
+    "flag.tests.task-per-describe": false,
+    "flag.tests.may-run-long": false,
+    "flag.tests.includes-optional": false
+  }
+}

exercises/practice/largest-series-product/.meta/proof.ci.wat

@@ -0,0 +1,77 @@
+(module
+  (memory (export "mem") 1)
+
+  (global $ZERO i32 (i32.const 48))
+
+  ;;
+  ;; Calculate the largest product for a contiguous substring of digits of length n.
+  ;;
+  ;; @param {i32} offset - offset of string in linear memory
+  ;; @param {i32} length - length of string in linear memory
+  ;;
+  ;; @returns {i32} largest digit product
+  ;;
+  (func (export "largestProduct") (param $offset i32) (param $length i32) (param $span i32) (result i32)
+    (local $product i32)
+    (local $stop i32)
+    (local $start i32)
+    (local $result i32)
+    (local $index i32)
+    (local $digit i32)
+
+    (if (i32.or (i32.lt_s (local.get $span) (i32.const 0))
+                (i32.gt_s (local.get $span) (local.get $length))) (then
+      (return (i32.const -1))
+    ))
+
+    (if (i32.eqz (local.get $length)) (then
+      (return (i32.const 1))
+    ))
+
+    (local.set $stop (i32.add (local.get $offset) (local.get $length)))
+
+    (local.set $index (local.get $offset))
+    (loop
+      (local.set $digit (i32.sub (i32.load8_u (local.get $index))
+                                 (global.get $ZERO)))
+      (if (i32.gt_u (local.get $digit) (i32.const 9)) (then
+        ;; $digit is not a valid digit.
+        (return (i32.const -1))
+      ))
+      (i32.store8 (local.get $index) (local.get $digit))
+
+      (local.set $index (i32.add (local.get $index) (i32.const 1)))
+      (br_if 0 (i32.lt_u (local.get $index) (local.get $stop)))
+    )
+
+    (if (i32.eqz (local.get $span)) (then
+      (return (i32.const 1))
+    ))
+
+    (local.set $result (i32.const 0))
+
+    (local.set $start (i32.sub (local.get $stop) (local.get $span)))
+    (loop $outer
+      (local.set $product (i32.const 1))
+      (local.set $index (local.get $start))
+      (loop $inner
+        (local.set $product (i32.mul (local.get $product)
+                                     (i32.load8_u (local.get $index))))
+        (local.set $index (i32.add (local.get $index) (i32.const 1)))
+        (br_if $inner (i32.lt_u (local.get $index) (local.get $stop)))
+      )
+      (if (i32.lt_u (local.get $result) (local.get $product)) (then
+        (local.set $result (local.get $product))
+      ))
+
+      (if (i32.eq (local.get $start) (local.get $offset)) (then
+        (return (local.get $result))
+      ))
+
+      (local.set $start (i32.sub (local.get $start) (i32.const 1)))
+      (local.set $stop (i32.sub (local.get $stop) (i32.const 1)))
+      (br $outer)
+    )
+    (unreachable)
+  )
+)

exercises/practice/largest-series-product/.meta/tests.toml

@@ -0,0 +1,60 @@
+# 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.
+
+[7c82f8b7-e347-48ee-8a22-f672323324d4]
+description = "finds the largest product if span equals length"
+
+[88523f65-21ba-4458-a76a-b4aaf6e4cb5e]
+description = "can find the largest product of 2 with numbers in order"
+
+[f1376b48-1157-419d-92c2-1d7e36a70b8a]
+description = "can find the largest product of 2"
+
+[46356a67-7e02-489e-8fea-321c2fa7b4a4]
+description = "can find the largest product of 3 with numbers in order"
+
+[a2dcb54b-2b8f-4993-92dd-5ce56dece64a]
+description = "can find the largest product of 3"
+
+[673210a3-33cd-4708-940b-c482d7a88f9d]
+description = "can find the largest product of 5 with numbers in order"
+
+[02acd5a6-3bbf-46df-8282-8b313a80a7c9]
+description = "can get the largest product of a big number"
+
+[76dcc407-21e9-424c-a98e-609f269622b5]
+description = "reports zero if the only digits are zero"
+
+[6ef0df9f-52d4-4a5d-b210-f6fae5f20e19]
+description = "reports zero if all spans include zero"
+
+[5d81aaf7-4f67-4125-bf33-11493cc7eab7]
+description = "rejects span longer than string length"
+
+[06bc8b90-0c51-4c54-ac22-3ec3893a079e]
+description = "reports 1 for empty string and empty product (0 span)"
+
+[3ec0d92e-f2e2-4090-a380-70afee02f4c0]
+description = "reports 1 for nonempty string and empty product (0 span)"
+
+[6d96c691-4374-4404-80ee-2ea8f3613dd4]
+description = "rejects empty string and nonzero span"
+
+[7a38f2d6-3c35-45f6-8d6f-12e6e32d4d74]
+description = "rejects invalid character in digits"
+
+[5fe3c0e5-a945-49f2-b584-f0814b4dd1ef]
+description = "rejects negative span"
+include = false
+
+[c859f34a-9bfe-4897-9c2f-6d7f8598e7f0]
+description = "rejects negative span"
+reimplements = "5fe3c0e5-a945-49f2-b584-f0814b4dd1ef"

exercises/practice/largest-series-product/.npmrc

@@ -0,0 +1 @@
+audit=false

exercises/practice/largest-series-product/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 Exercism
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

exercises/practice/largest-series-product/babel.config.js

@@ -0,0 +1,4 @@
+export default {
+  presets: ["@exercism/babel-preset-javascript"],
+  plugins: [],
+};