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keiravillekodekeiravillekode
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rename binary-search to binary-chop (#288)
Avoid collision with Factor's binary-search vocab. https://forum.exercism.org/t/factor-track-feedback/60226/17
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‎config.json‎

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"difficulty": 3
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},
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{
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"slug": "binary-search",
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"slug": "binary-chop",
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"name": "Binary Search",
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"uuid": "ea3a619c-0d03-4688-821a-22379470d7e1",
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"uuid": "49cc7b5c-d2fc-4332-89a5-9890c340f25f",
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"practices": [
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"recursion"
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],
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],
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"difficulty": 3
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},
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{
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"slug": "binary-search",
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"name": "Binary Search (deprecated)",
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"uuid": "ea3a619c-0d03-4688-821a-22379470d7e1",
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"practices": [],
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"prerequisites": [],
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"difficulty": 3,
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"status": "deprecated"
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},
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{
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"slug": "bob",
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"name": "Bob",

‎exercises/practice/binary-chop/.docs/instructions.md‎

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# Instructions
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Your task is to implement a binary search algorithm.
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A binary search algorithm finds an item in a list by repeatedly splitting it in half, only keeping the half which contains the item we're looking for.
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It allows us to quickly narrow down the possible locations of our item until we find it, or until we've eliminated all possible locations.
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~~~~exercism/caution
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Binary search only works when a list has been sorted.
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~~~~
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The algorithm looks like this:
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- Find the middle element of a _sorted_ list and compare it with the item we're looking for.
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- If the middle element is our item, then we're done!
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- If the middle element is greater than our item, we can eliminate that element and all the elements **after** it.
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- If the middle element is less than our item, we can eliminate that element and all the elements **before** it.
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- If every element of the list has been eliminated then the item is not in the list.
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- Otherwise, repeat the process on the part of the list that has not been eliminated.
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Here's an example:
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Let's say we're looking for the number 23 in the following sorted list: `[4, 8, 12, 16, 23, 28, 32]`.
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- We start by comparing 23 with the middle element, 16.
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- Since 23 is greater than 16, we can eliminate the left half of the list, leaving us with `[23, 28, 32]`.
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- We then compare 23 with the new middle element, 28.
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- Since 23 is less than 28, we can eliminate the right half of the list: `[23]`.
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- We've found our item.

‎exercises/practice/binary-chop/.docs/introduction.md‎

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# Introduction
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You have stumbled upon a group of mathematicians who are also singer-songwriters.
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They have written a song for each of their favorite numbers, and, as you can imagine, they have a lot of favorite numbers (like [0][zero] or [73][seventy-three] or [6174][kaprekars-constant]).
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You are curious to hear the song for your favorite number, but with so many songs to wade through, finding the right song could take a while.
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Fortunately, they have organized their songs in a playlist sorted by the title — which is simply the number that the song is about.
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You realize that you can use a binary search algorithm to quickly find a song given the title.
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[zero]: https://en.wikipedia.org/wiki/0
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[seventy-three]: https://en.wikipedia.org/wiki/73_(number)
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[kaprekars-constant]: https://en.wikipedia.org/wiki/6174_(number)

‎exercises/practice/binary-chop/.meta/config.json‎

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{
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"authors": [
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"keiravillekode"
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],
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"files": {
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"solution": [
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"binary-chop/binary-chop.factor"
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],
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"test": [
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"binary-chop/binary-chop-tests.factor"
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],
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"example": [
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".meta/example.factor"
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]
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},
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"blurb": "Implement a binary search algorithm.",
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"source": "Wikipedia",
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"source_url": "https://en.wikipedia.org/wiki/Binary_search_algorithm"
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}

‎exercises/practice/binary-chop/.meta/example.factor‎

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USING: combinators kernel locals math sequences ;
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IN: binary-chop
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ERROR: value-not-in-array ;
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:: search-range ( array value low high -- index )
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low high > [ value-not-in-array ] [
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low high + 2 /i :> mid
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mid array nth :> probe
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{
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{ [ probe value = ] [ mid ] }
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{ [ probe value < ] [ array value mid 1 + high search-range ] }
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[ array value low mid 1 - search-range ]
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} cond
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] if ;
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: find ( array value -- index )
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over length 1 - [ 0 ] dip search-range ;

‎exercises/practice/binary-chop/.meta/generator.jl‎

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module BinarySearch
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function gen_test_case(case)
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array = format_int_array(case["input"]["array"])
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value = to_int_str(case["input"]["value"])
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expected = case["expected"]
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if expected isa AbstractDict && haskey(expected, "error")
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return """[ $(array) $(value) find ] [ value-not-in-array? ] must-fail-with"""
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end
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return "{ $(to_int_str(expected)) }\n[ $(array) $(value) find ] unit-test"
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end
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end

‎exercises/practice/binary-chop/.meta/tests.toml‎

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# This is an auto-generated file.
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#
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# Regenerating this file via `configlet sync` will:
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# - Recreate every `description` key/value pair
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# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
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# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
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# - Preserve any other key/value pair
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#
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# As user-added comments (using the # character) will be removed when this file
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# is regenerated, comments can be added via a `comment` key.
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[b55c24a9-a98d-4379-a08c-2adcf8ebeee8]
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description = "finds a value in an array with one element"
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[73469346-b0a0-4011-89bf-989e443d503d]
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description = "finds a value in the middle of an array"
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[327bc482-ab85-424e-a724-fb4658e66ddb]
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description = "finds a value at the beginning of an array"
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[f9f94b16-fe5e-472c-85ea-c513804c7d59]
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description = "finds a value at the end of an array"
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[f0068905-26e3-4342-856d-ad153cadb338]
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description = "finds a value in an array of odd length"
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[fc316b12-c8b3-4f5e-9e89-532b3389de8c]
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description = "finds a value in an array of even length"
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[da7db20a-354f-49f7-a6a1-650a54998aa6]
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description = "identifies that a value is not included in the array"
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[95d869ff-3daf-4c79-b622-6e805c675f97]
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description = "a value smaller than the array's smallest value is not found"
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[8b24ef45-6e51-4a94-9eac-c2bf38fdb0ba]
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description = "a value larger than the array's largest value is not found"
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[f439a0fa-cf42-4262-8ad1-64bf41ce566a]
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description = "nothing is found in an empty array"
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[2c353967-b56d-40b8-acff-ce43115eed64]
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description = "nothing is found when the left and right bounds cross"

‎exercises/practice/binary-chop/binary-chop/binary-chop-tests.factor‎

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USING: binary-chop exercism-tools io kernel tools.test unicode ;
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IN: binary-chop.tests
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"finds a value in an array with one element" description
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{ 0 }
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[ { 6 } 6 find ] unit-test
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STOP-HERE
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"finds a value in the middle of an array" description
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{ 3 }
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[ { 1 3 4 6 8 9 11 } 6 find ] unit-test
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"finds a value at the beginning of an array" description
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{ 0 }
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[ { 1 3 4 6 8 9 11 } 1 find ] unit-test
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"finds a value at the end of an array" description
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{ 6 }
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[ { 1 3 4 6 8 9 11 } 11 find ] unit-test
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"finds a value in an array of odd length" description
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{ 9 }
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[ { 1 3 5 8 13 21 34 55 89 144 233 377 634 } 144 find ] unit-test
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"finds a value in an array of even length" description
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{ 5 }
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[ { 1 3 5 8 13 21 34 55 89 144 233 377 } 21 find ] unit-test
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"identifies that a value is not included in the array" description
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[ { 1 3 4 6 8 9 11 } 7 find ] [ value-not-in-array? ] must-fail-with
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"a value smaller than the array's smallest value is not found" description
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[ { 1 3 4 6 8 9 11 } 0 find ] [ value-not-in-array? ] must-fail-with
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"a value larger than the array's largest value is not found" description
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[ { 1 3 4 6 8 9 11 } 13 find ] [ value-not-in-array? ] must-fail-with
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"nothing is found in an empty array" description
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[ { } 1 find ] [ value-not-in-array? ] must-fail-with
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"nothing is found when the left and right bounds cross" description
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[ { 1 2 } 0 find ] [ value-not-in-array? ] must-fail-with

‎exercises/practice/binary-chop/binary-chop/binary-chop.factor‎

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USING: kernel ;
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IN: binary-chop
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ERROR: value-not-in-array ;
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: find ( array value -- index )
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"unimplemented" throw ;

‎exercises/practice/binary-chop/exercism-tools/exercism-tools.factor‎

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USING: accessors command-line continuations debugger io kernel
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lexer namespaces prettyprint.config sequences
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source-files.errors.debugger system tools.test vocabs
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vocabs.loader ;
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IN: exercism-tools
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SYNTAX: STOP-HERE
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lexer get [ text>> length ] keep line<< ;
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SYNTAX: TASK:
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lexer get next-line ;
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! Label the test that follows with its description.
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: description ( str -- )
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"###DESC### " write print ;
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! Print one failure block in a stable, parser-friendly form.
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:: print-failure ( failure -- )
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"###FAIL_BEGIN###" print
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failure error-location print
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[ failure error>> [ error. ] [ 2drop ] recover ] without-limits
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"###FAIL_END###" print
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flush ;
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: print-failures ( -- )
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test-failures get [ print-failure ] each ;
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: run-exercism-tests ( -- )
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vocab-roots [ "." prefix ] change-global
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command-line get first
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[ require ] [ test ] bi
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test-failures get empty?
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[ 0 exit ] [ print-failures 1 exit ] if ;
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MAIN: run-exercism-tests

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