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Knapsack problem/Continuous: Difference between revisions

Knapsack problem/Continuous (view source)

Revision as of 10:33, 31 October 2013

30 bytes added ,  10 years ago
Updated first D entry
(Added Erlang)
(Updated first D entry)
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=={{header|D}}==
<lang d>import std.stdio, std.algorithm, std.string, std.conv;
 
struct Item {
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real amount, value;
 
@property real valuePerKG() @safe const pure nothrow {
return value / amount;
}
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}
 
real sumsumBy(string field)(in Item[] items) @safe pure nothrow {
return reduce!("a + b." ~ field)(0.0L, items);
}
 
void main() {
Item[]const rawitems = [{Item("beef", 3.8, 36.0}),
{ Item("pork", 5.4, 43.0}),
{ Item("ham", 3.6, 90.0}),
{ Item("greaves", 2.4, 45.0}),
{ Item("flitch", 4.0, 30.0}),
{ Item("brawn", 2.5, 56.0}),
{ Item("welt", 3.7, 67.0}),
{ Item("salami", 3.0, 95.0}),
{ Item("sausage", 5.9, 98.0})];
.schwartzSort!(it => -it.valuePerKG)
 
// Reverse sorted by Value per amount .release;
const items = raw.sort!q{a.valuePerKG > b.valuePerKG}.release;
 
immutable(Item)[] chosen;
real space = 15.0;
foreach (const item; items)
if (item.amount < space) {
chosen ~= item;
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writefln("%10s %7s %7s %7s", "ITEM", "AMOUNT", "VALUE", "$/unit");
writefln("%(%s\n%)", chosen);
Item("TOTAL", chosen.sumsumBy!"amount", chosen.sumsumBy!"value").writeln;
}</lang>
{{out}}
Retrieved from "https://rosettacode.org/wiki/Special:MobileDiff/141094"
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