private static ChangeOptionList SetUpInitialPossibleChangeOptions()
{
var changeObjectList = new ChangeOptionList();
changeObjectList.AddChangeOption(0);
return(changeObjectList);
}
private static void ConsiderPossibleChangeOptionsForCoin(int target, ChangeOptionList possibleChangeOptions, int coin)
{
for (int subTarget = coin; subTarget <= target; ++subTarget)
{
var changeOption = GetPossibleChangeOptionWhenCoinSubtractedFromSubTarget(possibleChangeOptions, coin, subTarget);
if (ExistingChangeOptionShouldBeUpdated(possibleChangeOptions, subTarget, changeOption))
{
UpdateChangeOption(possibleChangeOptions, subTarget, coin, changeOption);
}
}
}
private static void UpdateChangeOption(ChangeOptionList possibleChangeOptions, int targetValue, int coin, ChangeOption existingChangeOption)
{
var newCoinList = CreateNewCoinList(coin, existingChangeOption);
if (!possibleChangeOptions.ChangeOptionExistsForTargetValue(targetValue))
{
possibleChangeOptions.AddChangeOption(targetValue, newCoinList);
}
else
{
possibleChangeOptions.GetChangeOption(targetValue).SetChangeCoins(newCoinList);
}
}
private static ChangeOption GetPossibleChangeOptionWhenCoinSubtractedFromSubTarget(ChangeOptionList possibleChangeOptions, int coin, int subtarget)
{
int targetAfterCoinStubtracted = subtarget - coin;
return(possibleChangeOptions.GetChangeOption(targetAfterCoinStubtracted));
}
private static bool ExactChangeCanBeGiven(ChangeOptionList possibleChangeOptions, int target)
{
return(possibleChangeOptions.ChangeOptionExistsForTargetValue(target));
}
private static bool ExistingChangeOptionShouldBeUpdated(ChangeOptionList existingChangeOptions, int subtarget, ChangeOption newChangeOption)
{
return(newChangeOption != null &&
(!existingChangeOptions.ChangeOptionExistsForTargetValue(subtarget) || NewChangeOptionIsShorter(existingChangeOptions.GetChangeOption(subtarget), newChangeOption)));
}