Question

I have approximately 100 tips that I need to display randomly on a site, different tip each day, and there is no access to a database. I have thought about putting the tips into array groups and associating each group with a day of the month, but that would not make the tips show up randomly. What is a relatively painless way to accomplish this task?

Answer 1

Since you want to display only one tip a day, and you can’t store any state, you can do the following:

1. Sort the tips using some deterministic method.
2. Seed a random number generator with today’s date.
3. Display the i^th tip where i = random.Next(numTips)
4. Repeat this whole process (including reseeding the random number generator) each time.

If you also want to ensure each tip is displayed at least once before a tip is repeated:

1. Seed a random number generator with a constant value (not the current time, this is important).

2. Shuffle the elements with Fisher-Yates, using the not-so-random number generator you created. Or use LINQ:

   tips.OrderBy(x => random.Next()).ToArray();
   

3. Display the i^th tip mod tips.Length where i is the number of days since Epoch.