A-M baby

Task/Knapsack-problem-Continuous/Tcl/knapsack-problem-continuous-1.tcl

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+package require Tcl 8.5
+
+# Uses the trivial greedy algorithm
+proc continuousKnapsack {items massLimit} {
+    # Add in the unit prices
+    set idx -1
+    foreach item $items {
+	lassign $item name mass value
+	lappend item [expr {$value / $mass}]
+	lset items [incr idx] $item
+    }
+
+    # Sort by unit prices
+    set items [lsort -decreasing -real -index 3 $items]
+
+    # Add items, using most valuable-per-unit first
+    set result {}
+    set total 0.0
+    set totalValue 0
+    foreach item $items {
+	lassign $item name mass value unit
+	if {$total + $mass < $massLimit} {
+	    lappend result [list $name $mass $value]
+	    set total [expr {$total + $mass}]
+	    set totalValue [expr {$totalValue + $value}]
+	} else {
+	    set mass [expr {$massLimit - $total}]
+	    set value [expr {$unit * $mass}]
+	    lappend result [list $name $mass $value]
+	    set totalValue [expr {$totalValue + $value}]
+	    break
+	}
+    }
+
+    # We return the total value too, purely for convenience
+    return [list $result $totalValue]
+}