Question

I have an algorithm question related to XP levels in games:

I have a table that lists level numbers, and number of XPs in that level:

GameLevel    ExperiencePointsInLevel
1            30
2            70
3            160
4            250

For each player, I only maintain their total XP, not any level info.
Given a player’s total XP, how do I determine the following via an algorithm (I’m using C# & LINQ)?

1. Current level of person
2. Number points the person has in this level

For example, if a player has 110 XPs, the answer would be:

1. Level 3
2. 10 XPs; (110-30-70 = 10)

Any ideas?

Cheers,

Dean

Answer 1

If experience points in level is changed to represent the total XP a player needs to reach that level.

Game Level    Experience Points
 1             0
 2             100
 3             200
 4             400

A more functional approach with LINQ would be something like the following:

var playerlevel = ExperiencePointsTable
    .Where(xpt => xpt.ExperiencePointsInLevel <= player.ExperiencePoints)
    .Select(xpt => xpt.GameLevel)
    .Max();

I think this simplifies the solution and avoids having to generate arrays for a look up.

Edit: fixed to check less than or equal to level.

To find out how many xp the player has to get to the next level you can use a similiar LINQ query.

var xpToNextLevel = (ExperiencePointsTable
    .Where(xpt => xpt.ExperiencePointsInLevel > player.ExperiencePoints)
    .Select(xpt => xpt.ExperiencePoints)
    .Min()) - player.ExperiencePoints;