Question

I want to create such class:

public TrackMaxMin(int periodInSec)

// use current system time as time
public Add(decimal value)

// return maximum Value for the last periodInSec
public Max { get {} }

// return minimum Value for the last periodInSec
public Min { get {} }

I think I can use FIFO query to store Pair<DateTime, decimal> and on each Add call I should:

• remove “outdated” values from query. when removing “update” cached Max/Min if needed
• add new value. update Max/Min if needed

My solution is trivial and straightforward. Probably you can suggest something better?

Answer 1

You can use a max-heap called max, a min-heap called min, and a queue called q.

Let x be an element with the properties x.time and x.val.

When Add is called:

• Create a new element x.
• Add x to all of the data structures.

The running time of Add is O(lgn).

When Max is called:

• max.GetMax()

The running time of Max is O(1).

When Min is called:

• min.GetMin()

The running time of Min is O(1).

For the maintenance of the model do this:

Have only one timer that is fired each time the period of the next to go out element in q is due.

When the period of x is due then:

• q.Dequeue(), max.Delete(x), min.Delete(x)