Add knapsack exercise (#183)
* Add `knapsack` exercise * Work * Tweak names * Update exercises/practice/knapsack/.meta/example.8th Co-authored-by: Glenn Jackman <glenn.jackman@gmail.com> * Rename --------- Co-authored-by: Glenn Jackman <glenn.jackman@gmail.com>
This commit is contained in:
Erik Schierboom
@@ -524,6 +524,14 @@
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"practices": [],
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"prerequisites": [],
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"difficulty": 3
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},
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{
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"slug": "knapsack",
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"name": "Knapsack",
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"uuid": "3123e9f2-0d91-4ddc-b67c-ad9340af859e",
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"practices": [],
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"prerequisites": [],
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"difficulty": 5
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}
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]
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},
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35
exercises/practice/knapsack/.docs/instructions.md
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35
exercises/practice/knapsack/.docs/instructions.md
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# Instructions
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In this exercise, let's try to solve a classic problem.
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Bob is a thief.
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After months of careful planning, he finally manages to crack the security systems of a high-class apartment.
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In front of him are many items, each with a value (v) and weight (w).
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Bob, of course, wants to maximize the total value he can get; he would gladly take all of the items if he could.
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However, to his horror, he realizes that the knapsack he carries with him can only hold so much weight (W).
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Given a knapsack with a specific carrying capacity (W), help Bob determine the maximum value he can get from the items in the house.
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Note that Bob can take only one of each item.
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All values given will be strictly positive.
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Items will be represented as a list of items.
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Each item will have a weight and value.
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For example:
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```none
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Items: [
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{ "weight": 5, "value": 10 },
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{ "weight": 4, "value": 40 },
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{ "weight": 6, "value": 30 },
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{ "weight": 4, "value": 50 }
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]
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Knapsack Limit: 10
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```
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For the above, the first item has weight 5 and value 10, the second item has weight 4 and value 40, and so on.
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In this example, Bob should take the second and fourth item to maximize his value, which, in this case, is 90.
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He cannot get more than 90 as his knapsack has a weight limit of 10.
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19
exercises/practice/knapsack/.meta/config.json
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exercises/practice/knapsack/.meta/config.json
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{
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"authors": [
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"erikschierboom"
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],
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"files": {
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"solution": [
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"knapsack.8th"
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],
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"test": [
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"test.8th"
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],
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"example": [
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".meta/example.8th"
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]
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},
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"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.",
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"source": "Wikipedia",
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"source_url": "https://en.wikipedia.org/wiki/Knapsack_problem"
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}
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17
exercises/practice/knapsack/.meta/example.8th
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exercises/practice/knapsack/.meta/example.8th
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: zeros \ n -- a
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n:1+ a:new 0 a:push swap a:smear
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;
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: update-maximum-for-item-and-weight \ n a m n -- n a m
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>r "weight" m:@ swap "value" m:@ rot r@ swap n:- fourth swap a:@ rot n:+
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r@ rot swap a:_@ n:max 2 roll r> rot a:! swap
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;
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: update-maximum-for-item \ n a m -- n a
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"weight" m:@ fourth ' update-maximum-for-item-and-weight -rot loop- drop
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;
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: maximum-value \ n a -- n
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over zeros swap
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' update-maximum-for-item a:each! drop swap a:_@
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;
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36
exercises/practice/knapsack/.meta/tests.toml
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exercises/practice/knapsack/.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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[a4d7d2f0-ad8a-460c-86f3-88ba709d41a7]
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description = "no items"
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include = false
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[3993a824-c20e-493d-b3c9-ee8a7753ee59]
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description = "no items"
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reimplements = "a4d7d2f0-ad8a-460c-86f3-88ba709d41a7"
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[1d39e98c-6249-4a8b-912f-87cb12e506b0]
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description = "one item, too heavy"
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[833ea310-6323-44f2-9d27-a278740ffbd8]
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description = "five items (cannot be greedy by weight)"
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[277cdc52-f835-4c7d-872b-bff17bab2456]
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description = "five items (cannot be greedy by value)"
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[81d8e679-442b-4f7a-8a59-7278083916c9]
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description = "example knapsack"
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[f23a2449-d67c-4c26-bf3e-cde020f27ecc]
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description = "8 items"
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[7c682ae9-c385-4241-a197-d2fa02c81a11]
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description = "15 items"
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3
exercises/practice/knapsack/knapsack.8th
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3
exercises/practice/knapsack/knapsack.8th
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: maximum-value \ n a -- n
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;
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173
exercises/practice/knapsack/libs/exercism/test
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173
exercises/practice/knapsack/libs/exercism/test
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needs console/loaded
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\ -----------------------------------------------------------------
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ns: test
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-1 var, test-count
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var tests-passed
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var tests-failed
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var tests-skipped
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true var, run-test
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\ Some utility words
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: test-passed \ s x x -- \\ test name, expected value, actual value
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2drop
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1 tests-passed n:+!
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con:green con:onBlack . space " ... OK" . con:white con:onBlack cr
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;
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: test-skipped \ s --
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1 tests-skipped n:+!
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con:cyan con:onBlack . space " ... SKIPPED" . con:white con:onBlack cr
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;
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: test-failed \ s x x -- \\ test name, expected value, actual value
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1 tests-failed n:+!
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rot
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con:red con:onBlack . space " ... FAIL" . con:white con:onBlack cr
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" Actual: «" . . "»" . cr
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" Expected: «" . . "»" . cr cr
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;
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: isword? \ x -- x f
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dup >kind ns:w n:=
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;
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: run-test? \ -- T
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run-test @ if true else "RUN_ALL_TESTS" getenv n:>bool then
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;
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\ Num passed + num skipped + num failed should == num tests
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: all-tests-run? \ -- T
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tests-passed @ tests-skipped @ tests-failed @ n:+ n:+
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test-count @ n:=
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;
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\ returns true if x is a date, false otherwise
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: date? \ x -- x T
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dup >kind ns:d n:=
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;
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\ adapted from 8th forum -- https://8th-dev.com/forum/index.php/topic,2745.0.html
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: eq? \ x x -- T
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\ are the items the same kind?
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2dup >kind swap >kind n:=
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!if 2drop false ;then
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\ same kind: try different comparators
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number? if n:= ;then
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string? if s:= ;then
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array? if ' eq? a:= 2nip ;then
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map? if ' eq? m:= 2nip ;then
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date? if d:= ;then
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\ otherwise fall back to 'lazy evaluation'
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l: =
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;
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: eps_eq? \ n x x -- T
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\ are the items the same kind?
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2dup >kind swap >kind n:=
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!if 2drop false ;then
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number? !if 2drop false ;then
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rot n:~=
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;
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: check-depth \ ... n -- ...
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dup>r
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n:1+ depth n:=
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!if
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con:red con:onBlack
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"PANIC: expected stack depth to be " . r> . cr
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"Stack is:" . cr
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.s cr
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255 die
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then
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rdrop
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;
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\ -----------------------------------------------------------------
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\ status report at end of run
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( all-tests-run?
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!if con:red con:onBlack "... FAIL - not all tests completed" . con:white con:onBlack cr then
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) onexit
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\ Print a summary of the tests run
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( con:white con:onBlack
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test-count @ . space "tests planned - " .
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tests-passed @ . space "passed - " .
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tests-skipped @ . space "skipped - " .
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tests-failed @ . space "failed" . cr
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) onexit
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\ -----------------------------------------------------------------
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\ The public-facing words
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\ -----------------------------------------------------------------
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: equal? \ s x w -- | s w x --
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run-test? !if 2drop test-skipped ;; then
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isword? !if swap then
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w:exec
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3 check-depth
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2dup \ so test-failed can show actual and expected
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eq? if test-passed else test-failed then
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;
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: approx_equal? \ s x w n -- | s w x n --
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run-test? !if 3drop test-skipped ;; then
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-rot isword? !if swap then
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w:exec
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4 check-depth
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3dup \ so test-failed can show actual and expected
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eps_eq?
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if rot drop test-passed else rot drop test-failed then
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;
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: true? \ s w --
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run-test? !if drop test-skipped ;; then
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w:exec
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2 check-depth
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true swap dup \ so test-failed can show actual and expected
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if test-passed else test-failed then
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;
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: false? \ s w --
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run-test? !if drop test-skipped ;; then
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w:exec
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2 check-depth
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false swap dup \ so test-failed can show actual and expected
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!if test-passed else test-failed then
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;
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: null? \ s w --
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run-test? !if drop test-skipped ;; then
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w:exec
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2 check-depth
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null swap dup \ so test-failed can show actual and expected
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G:null? nip if test-passed else test-failed then
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;
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: SKIP-REST-OF-TESTS false run-test ! ;
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: tests \ n --
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test-count !
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;
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\ Set the exit status:
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\ 0 = all OK
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\ 1 = not all tests were run (some error occurred)
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\ 2 = some tests failed
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: end-of-tests \ --
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all-tests-run?
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if
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tests-failed @ 0 n:= if 0 else 2 then
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else
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1
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then
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die
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;
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44
exercises/practice/knapsack/test.8th
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44
exercises/practice/knapsack/test.8th
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"knapsack.8th" f:include
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needs exercism/test
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with: test
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7 tests
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"no items"
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( 100 [] maximum-value )
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0
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equal?
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SKIP-REST-OF-TESTS
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"one item, too heavy"
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( 10 [{"weight": 100, "value": 1}] maximum-value )
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0
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equal?
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"five items (cannot be greedy by weight)"
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( 10 [{"weight": 2, "value": 5}, {"weight": 2, "value": 5}, {"weight": 2, "value": 5}, {"weight": 2, "value": 5}, {"weight": 10, "value": 21}] maximum-value )
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21
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equal?
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"five items (cannot be greedy by value)"
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( 10 [{"weight": 2, "value": 20}, {"weight": 2, "value": 20}, {"weight": 2, "value": 20}, {"weight": 2, "value": 20}, {"weight": 10, "value": 50}] maximum-value )
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80
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equal?
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"example knapsack"
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( 10 [{"weight": 5, "value": 10}, {"weight": 4, "value": 40}, {"weight": 6, "value": 30}, {"weight": 4, "value": 50}] maximum-value )
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90
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equal?
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"8 items"
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( 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}] maximum-value )
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900
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equal?
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"15 items"
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( 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}] maximum-value )
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1458
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equal?
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end-of-tests
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;with
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