任务占用时间的算法

Edit:
Steps:
Start at target day. 
Then move backwards until no events are carried over from another day.
From there, start counting hours, and keep track of carried over hours. 
Day cannot last more than ActualDayLength()
Then, once you know that, work your way back to target and then calculate actual occupied hours.
Edit:
Steps:
Start at target day. 
Then move ba