From 662e1614b5ca63e9137595785d7b99990b43a304 Mon Sep 17 00:00:00 2001 From: Katrina Owen Date: Tue, 16 May 2023 12:14:07 +0200 Subject: [PATCH] Sync largest-series-product docs with problem-specifications (#625) * Sync largest-series-product docs with problem-specifications The largest-series-product exercise has been overhauled as part of a project to make practice exercises more consistent and friendly. For more context, please see the discussion in the forum, as well as the pull request that updated the exercise in the problem-specifications repository: - https://forum.exercism.org/t/new-project-making-practice-exercises-more-consistent-and-human-across-exercism/3943 - https://github.com/exercism/problem-specifications/pull/2246 * Delete test cases from largest-series-product This deletes two deprecated test cases so that we can dramatically simplify the instructions for this exercise. --- .../.docs/instructions.md | 31 ++++++++++++------- .../.docs/introduction.md | 5 +++ .../largest-series-product/.meta/tests.toml | 2 ++ .../largest-series-product/runtests.jl | 8 ----- 4 files changed, 26 insertions(+), 20 deletions(-) create mode 100644 exercises/practice/largest-series-product/.docs/introduction.md diff --git a/exercises/practice/largest-series-product/.docs/instructions.md b/exercises/practice/largest-series-product/.docs/instructions.md index 1c200915..f297b57f 100644 --- a/exercises/practice/largest-series-product/.docs/instructions.md +++ b/exercises/practice/largest-series-product/.docs/instructions.md @@ -1,19 +1,26 @@ # Instructions -Given a string of digits, calculate the largest product for a contiguous substring of digits of length n. +Your task is to look for patterns in the long sequence of digits in the encrypted signal. -For example, for the input `"1027839564"`, the largest product for a series of 3 digits is 270 `(9 * 5 * 6)`, and the largest product for a series of 5 digits is 7560 `(7 * 8 * 3 * 9 * 5)`. +The technique you're going to use here is called the largest series product. -Note that these series are only required to occupy *adjacent positions* in the input; the digits need not be *numerically consecutive*. +Let's define a few terms, first. -For the input `"73167176531330624919225119674426574742355349194934"`, -the largest product for a series of 6 digits is 23520. +- **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 -For a series of zero digits, you need to return the empty product (the result of multiplying no numbers), which is 1. +Let's work through an example, with the input `"63915"`. -~~~~exercism/advanced -You do not need to understand why the empty product is 1 to solve this problem, -but in case you are interested, here is an informal argument: if we split a list of numbers `A` into two new lists `B` and `C`, then we expect `product(A) == product(B) * product(C)` because we don't expect the order that you multiply things to matter; now if we split a list containing only the number 3 into the empty list and a list containing the number 3 then the product of the empty list has to be 1 for `product([3]) == product([]) * product([3])` to be true. - -The same kind of argument justifies why the sum of no numbers is 0. -~~~~ +- 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**. diff --git a/exercises/practice/largest-series-product/.docs/introduction.md b/exercises/practice/largest-series-product/.docs/introduction.md new file mode 100644 index 00000000..597bb5fa --- /dev/null +++ b/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. diff --git a/exercises/practice/largest-series-product/.meta/tests.toml b/exercises/practice/largest-series-product/.meta/tests.toml index 6c111adf..88316925 100644 --- a/exercises/practice/largest-series-product/.meta/tests.toml +++ b/exercises/practice/largest-series-product/.meta/tests.toml @@ -41,9 +41,11 @@ description = "rejects span longer than string length" [06bc8b90-0c51-4c54-ac22-3ec3893a079e] description = "reports 1 for empty string and empty product (0 span)" +include = false [3ec0d92e-f2e2-4090-a380-70afee02f4c0] description = "reports 1 for nonempty string and empty product (0 span)" +include = false [6d96c691-4374-4404-80ee-2ea8f3613dd4] description = "rejects empty string and nonzero span" diff --git a/exercises/practice/largest-series-product/runtests.jl b/exercises/practice/largest-series-product/runtests.jl index 93241e52..1647c24c 100644 --- a/exercises/practice/largest-series-product/runtests.jl +++ b/exercises/practice/largest-series-product/runtests.jl @@ -38,14 +38,6 @@ end @test largest_product("99099", 3) == 0 end -@testset "reports 1 for empty string and empty product 0 span" begin - @test largest_product("", 0) == 1 -end - -@testset "reports 1 for nonempty string and empty product 0 span" begin - @test largest_product("123", 0) == 1 -end - @testset "error handling" begin @testset "span longer than string length" begin @test_throws ArgumentError largest_product("123", 4)