public ISack <T> Solve(IList <IItem <T> > items, long maxWeight)
{
var resultMatrix = new TwoDimensionalMatrix <long>();
var keepMatrix = new TwoDimensionalMatrix <bool>();
var weightArray = (from w in items select w.Weight).ToList();
var valueArray = (from v in items select v.Value).ToList();
var itemCount = items.Count;
for (var i = 1; i <= itemCount; i++)
{
var weightAtIndex = weightArray[i - 1];
var valueAtIndex = valueArray[i - 1];
for (var w = 0; w <= maxWeight; w++)
{
var newValue = resultMatrix[i, w - 1] + valueAtIndex;
var previousValue = resultMatrix[i - 1, w];
if (weightAtIndex <= w && newValue > previousValue)
{
resultMatrix[i, w] = newValue;
keepMatrix[i, w] = true;
}
else
{
resultMatrix[i, w] = previousValue;
}
}
}
var duplicateSack = new DuplicateAllowedSack <T>(maxWeight);
/*
* 1. Find the max value at the max weight
* 2. Figure out which items added to the max value
* 3. Count them
* 4. Add them to the bag
*/
for (var i = 1; i <= itemCount; i++)
{
if (keepMatrix[i, maxWeight])
{
//Count how many times we should add it to the sack
for (var j = 0; j <= maxWeight; j++)
{
if (keepMatrix[i, j])
{
duplicateSack.AddItem(items[i - 1]); //The index for the item array is off by one
}
}
}
}
return(duplicateSack);
}
public ISack <T> Solve(IList <IItem <T> > items, long maxWeight)
{
var resultMatrix = new TwoDimensionalMatrix <long>();
var keepMatrix = new TwoDimensionalMatrix <bool>();
var itemCount = items.Count;
for (var i = 1; i <= itemCount; i++)
{
var weightAtIndex = items[i - 1].Weight;
var valueAtIndex = items[i - 1].Value;
for (var w = 0; w <= maxWeight; w++)
{
var newValue = valueAtIndex + resultMatrix[i - 1, w - weightAtIndex];
var oldValue = resultMatrix[i - 1, w];
if (weightAtIndex <= w && newValue > oldValue)
{
resultMatrix[i, w] = newValue;
keepMatrix[i, w] = true;
}
else
{
resultMatrix[i, w] = oldValue;
}
}
}
var defaultSack = new Sack <T>(maxWeight);
var upperBound = maxWeight;
for (var i = items.Count; i > 0; i--)
{
if (keepMatrix[i, upperBound])
{
defaultSack.AddItem(items[i - 1]);
upperBound -= items[i - 1].Weight;
}
}
return(defaultSack);
}