Question

Is there a formula or algorithm which can prioritize items based on weight and a date? For instance, a critical item would always be at the top of the list while a two normal items would be prioritized based on their due date.

Answer 1

Yes. This can either be done by defining a comparison function that checks priority first. I.e.

// Returns n < 0, 0, or n > 1 if value1 is less than, equal to or greater
compare(value1, value2) {
  if(value1.priority != value2.priority) {
    return value1.priority - value2.priority;
  }
  return value1.date - value2.date;
}

Alternatively, this function returns a value calculated from the date and the priority, this can be used to compare tasks and order them by priority (and then date):

// Returns
task.GetValue() {
  return me.GetDateAsIntegerValue() + MAX_DATE_VALUE * me.GetPriority();
}

But just as sarnold mentioned, this is a highly studied area.