Knapsack problem/Continuous: Difference between revisions
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(Added Erlang) |
(Updated first D entry) |
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=={{header|D}}== |
=={{header|D}}== |
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<lang d>import std.stdio, std.algorithm, std.string |
<lang d>import std.stdio, std.algorithm, std.string; |
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struct Item { |
struct Item { |
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real amount, value; |
real amount, value; |
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@property real valuePerKG() const pure nothrow { |
@property real valuePerKG() @safe const pure nothrow { |
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return value / amount; |
return value / amount; |
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} |
} |
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} |
} |
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real |
real sumBy(string field)(in Item[] items) @safe pure nothrow { |
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return reduce!("a + b." ~ field)(0.0L, items); |
return reduce!("a + b." ~ field)(0.0L, items); |
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} |
} |
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void main() { |
void main() { |
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const items = [Item("beef", 3.8, 36.0), |
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Item("pork", 5.4, 43.0), |
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Item("ham", 3.6, 90.0), |
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Item("greaves", 2.4, 45.0), |
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Item("flitch", 4.0, 30.0), |
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Item("brawn", 2.5, 56.0), |
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Item("welt", 3.7, 67.0), |
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Item("salami", 3.0, 95.0), |
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Item("sausage", 5.9, 98.0)] |
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.schwartzSort!(it => -it.valuePerKG) |
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.release; |
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const items = raw.sort!q{a.valuePerKG > b.valuePerKG}.release; |
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immutable(Item)[] chosen; |
immutable(Item)[] chosen; |
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real space = 15.0; |
real space = 15.0; |
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foreach (item; items) |
foreach (const item; items) |
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if (item.amount < space) { |
if (item.amount < space) { |
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chosen ~= item; |
chosen ~= item; |
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writefln("%10s %7s %7s %7s", "ITEM", "AMOUNT", "VALUE", "$/unit"); |
writefln("%10s %7s %7s %7s", "ITEM", "AMOUNT", "VALUE", "$/unit"); |
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writefln("%(%s\n%)", chosen); |
writefln("%(%s\n%)", chosen); |
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Item("TOTAL", chosen. |
Item("TOTAL", chosen.sumBy!"amount", chosen.sumBy!"value").writeln; |
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}</lang> |
}</lang> |
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{{out}} |
{{out}} |
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