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Add knapsack exercise
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‎config.json‎

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"prerequisites": [],
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"difficulty": 5
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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": "3a56fade-68b2-4f6a-bb73-d13c4af3aa68",
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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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"slug": "largest-series-product",
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"name": "Largest Series Product",

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

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# Instructions
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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.
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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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All values given will be strictly positive.
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Lhakpa can take only one of each item.
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For example:
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```text
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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 Maximum Weight: 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, Lhakpa should take the second and fourth item to maximize her value, which, in this case, is 90.
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She cannot get more than 90 as her knapsack has a weight limit of 10.

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

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

‎exercises/practice/knapsack/.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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"Knapsack.pas"
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],
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"test": [
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"TestCases.pas"
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],
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"example": [
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".meta/example.pas"
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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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}

‎exercises/practice/knapsack/.meta/example.pas‎

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unit Knapsack;
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{$mode ObjFPC}{$H+}
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interface
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type
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TItem = record
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weight: Integer;
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value: Integer;
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end;
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TItemArray = Array Of TItem;
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TIntArray = Array Of Integer;
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function maximumValue(const maximumWeight : Integer; const items : TItemArray) : Integer;
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implementation
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uses SysUtils;
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function maximumValue(const maximumWeight : Integer; const items : TItemArray) : Integer;
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var
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table : TIntArray = ();
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itemIndex : Integer;
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index : Integer;
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value : Integer;
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begin
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SetLength(table, maximumWeight + 1);
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for index := Low(table) to High(table) do
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table[index] := 0;
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for itemIndex := Low(items) to High(items) do
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begin
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index := maximumWeight + 1;
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while index > items[itemIndex].weight do
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begin
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index := index - 1;
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value := items[itemIndex].value + table[index - items[itemIndex].weight];
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if table[index] < value then
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table[index] := value;
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end;
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end;
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result := table[maximumWeight];
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end;
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end.

‎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"

‎exercises/practice/knapsack/Knapsack.pas‎

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unit Knapsack;
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{$mode ObjFPC}{$H+}
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interface
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type
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TItem = record
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weight: Integer;
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value: Integer;
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end;
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TItemArray = Array Of TItem;
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function maximumValue(const maximumWeight : Integer; const items : TItemArray) : Integer;
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implementation
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uses SysUtils;
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function maximumValue(const maximumWeight : Integer; const items : TItemArray) : Integer;
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begin
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raise ENotImplemented.Create('Please implement your solution.'); result := maximumWeight + length(items);
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end;
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end.

‎exercises/practice/knapsack/Makefile‎

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SHELL = /bin/bash
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MAKEFLAGS += --no-print-directory
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DESTDIR = build
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EXECUTABLE = $(DESTDIR)/test
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COMMAND = fpc -l- -v0 -g -gl -Sa -Cr -Sehnw -Fu./lib test.pas -FE"./$(DESTDIR)"
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.ONESHELL:
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test:
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@mkdir -p "./$(DESTDIR)"
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@cp -r ./lib "./$(DESTDIR)"
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@$(COMMAND) && ./$(EXECUTABLE) $(test)
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clean:
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@rm -fr "./$(DESTDIR)"

‎exercises/practice/knapsack/TestCases.pas‎

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unit TestCases;
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{$mode ObjFPC}{$H+}
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interface
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uses Classes, SysUtils, FPCUnit, TestRegistry, FPCUnitTestUtils;
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type
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KnapsackTest = class(TTestCase)
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published
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procedure no_items;
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procedure one_item_too_heavy;
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procedure five_items_cannot_be_greedy_by_weight;
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procedure five_items_cannot_be_greedy_by_value;
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procedure example_knapsack;
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procedure _8_items;
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procedure _15_items;
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end;
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implementation
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uses Knapsack;
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// 3993a824-c20e-493d-b3c9-ee8a7753ee59
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procedure KnapsackTest.no_items;
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const
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items : TItemArray = (
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);
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begin
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TapAssertTrue(Self, 'no items', 0, Knapsack.maximumValue(100, items));
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end;
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// 1d39e98c-6249-4a8b-912f-87cb12e506b0
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procedure KnapsackTest.one_item_too_heavy;
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const
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items : TItemArray = (
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(weight: 100; value: 1)
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);
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begin
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TapAssertTrue(Self, 'one item, too heavy', 0, Knapsack.maximumValue(10, items));
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end;
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// 833ea310-6323-44f2-9d27-a278740ffbd8
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procedure KnapsackTest.five_items_cannot_be_greedy_by_weight;
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const
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items : TItemArray = (
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(weight: 2; value: 5),
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(weight: 2; value: 5),
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(weight: 2; value: 5),
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(weight: 2; value: 5),
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(weight: 10; value: 21)
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);
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begin
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TapAssertTrue(Self, 'five items (cannot be greedy by weight)', 21, Knapsack.maximumValue(10, items));
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end;
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// 277cdc52-f835-4c7d-872b-bff17bab2456
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procedure KnapsackTest.five_items_cannot_be_greedy_by_value;
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const
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items : TItemArray = (
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(weight: 2; value: 20),
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(weight: 2; value: 20),
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(weight: 2; value: 20),
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(weight: 2; value: 20),
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(weight: 10; value: 50)
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);
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begin
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TapAssertTrue(Self, 'five items (cannot be greedy by value)', 80, Knapsack.maximumValue(10, items));
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end;
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// 81d8e679-442b-4f7a-8a59-7278083916c9
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procedure KnapsackTest.example_knapsack;
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const
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items : TItemArray = (
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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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begin
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TapAssertTrue(Self, 'example knapsack', 90, Knapsack.maximumValue(10, items));
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end;
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// f23a2449-d67c-4c26-bf3e-cde020f27ecc
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procedure KnapsackTest._8_items;
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const
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items : TItemArray = (
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(weight: 25; value: 350),
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(weight: 35; value: 400),
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(weight: 45; value: 450),
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(weight: 5; value: 20),
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(weight: 25; value: 70),
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(weight: 3; value: 8),
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(weight: 2; value: 5),
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(weight: 2; value: 5)
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);
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begin
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TapAssertTrue(Self, '8 items', 900, Knapsack.maximumValue(104, items));
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end;
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// 7c682ae9-c385-4241-a197-d2fa02c81a11
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procedure KnapsackTest._15_items;
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const
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items : TItemArray = (
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(weight: 70; value: 135),
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(weight: 73; value: 139),
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(weight: 77; value: 149),
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(weight: 80; value: 150),
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(weight: 82; value: 156),
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(weight: 87; value: 163),
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(weight: 90; value: 173),
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(weight: 94; value: 184),
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(weight: 98; value: 192),
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(weight: 106; value: 201),
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(weight: 110; value: 210),
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(weight: 113; value: 214),
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(weight: 115; value: 221),
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(weight: 118; value: 229),
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(weight: 120; value: 240)
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);
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begin
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TapAssertTrue(Self, '15 items', 1458, Knapsack.maximumValue(750, items));
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end;
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initialization
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RegisterTest(KnapsackTest);
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end.

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