Thinking about the probability of drawing cards in the duel link of game king

I prefer to play the game king duel link , But as a programmer, I sometimes think about how to realize the functions in the game , Because I also want to be a game server engineer , This article shares my discussion and Simulation of the probability of using gem cards to draw card types

This game draws four types of cards , Extraordinary card , Rare cards , Precious card , Ordinary card , Let's add up the probability of these four types of cards 100%, Of course, the number of each is determined by the planning , Just read the configuration table directly . Since it adds up to 100%, Then use 1～100 The integer of represents the range of probabilities of various card types , for example ： The probability of drawing an extraordinary card is 3%, So the probability range is ：1～3; The probability of drawing a rare card is 5%, So the probability range is ：4～8; The probability of drawing precious cards is 20%, So the probability range is ：9～28; The probability of drawing an ordinary card is 72%, So the probability range is ：29～100; Each time a card is drawn, a random 1～100 Integer between , The range of this integer is the type of card drawn

@Data
public class CardType {
    
    private String type; // Card type 
    private int probability;// Draw probability 
    private int min;// Minimum probability range 
    private int max;// Maximum probability range 

    public CardType(String type, int probability) {
    
        this.type = type;
        this.probability = probability;
    }
}

The interesting thing about the game itself is randomness , But sometimes, in order to retain users, they will also be random , such as ： Some players may smoke when they are lucky 10 You can draw several extraordinary cards with a second card , Some players have bad luck and even draw 100 If you can't get the super player every time, the game may lose this player , Therefore, the probability of human interference ： for example ,1: Set the probability guarantee times of an extraordinary card , If the number of times a player draws a card continuously without drawing an extraordinary card reaches the minimum number of times , The system forces the player to obtain , After that, the minimum number of times is reset ;2: Set card drawing n The maximum number of times you can get an extraordinary card in times , Like smoking 100 Second card , But set the minimum number of guarantee for the extraordinary card to 10, Users can get 10 Zhang Chaofan card , I feel that the user has earned , If it is specified to smoke 100 Get... At most times 5 Zhang Chaofan card , It is not affected by the number of guaranteed times . Personally, I think the rules 1 Generally, it is aimed at users who draw cards less often at a time , The rules 2 It is generally aimed at those local tyrants ; Anyway, we can make flexible methods , The following is the simulation implementation I want ：

/** *  Simulation of the game king duel link in the draw card probability problem  */
public class RateRandomNumber {
    

    // Use LinkedHashMap reason , Make sure the lowest probability comes first （ Logical needs ）
    public static Map<String,CardType> cardTypes = new LinkedHashMap<>();

    /** * @description:  Initialization data  * @return: * @author: Ming * @time: 2022/6/9 */
    static {
    
        cardTypes.put(" Extraordinary ",new CardType(" Extraordinary ",3));
        cardTypes.put(" rare ",new CardType(" rare ",5));
        cardTypes.put(" Precious ",new CardType(" Precious ",20));
        cardTypes.put(" Ordinary ",new CardType(" Ordinary ",72));
        setCardProbabilityRang();
    }


    /** * @description:  Set the probability range according to the probability  *  explain ： *  Card drawing is random generation 1 To 100 Integer between , Because the total probability of various card types is 100%, Here is to 1～100 The number of indicates the probability range of various card types , *  for example ： Extraordinary card probability %3, Then the probability range is 1～3, Precious card probability %5, Then the probability range is 4～8, And so on , Finally, the range of randomly generated integers is the type of card drawn  * @return: * @author: Ming * @time: 2022/6/9 */
    public static void setCardProbabilityRang(){
    
        int preMax = 0;// The maximum value of the probability range of the previous element 
        for (Map.Entry<String,CardType> m: cardTypes.entrySet()){
    
            CardType cardType = m.getValue();
            int max = cardType.getProbability()+preMax;// The maximum value of the current card probability range is ： Probability of current card + The maximum value of the probability range of the previous element 
            cardType.setMax(max);
            cardType.setMin(preMax+1);// The minimum value of the current card probability range is ： The maximum value of the probability range of the previous element +1
            preMax = max;
        }
    }


    /** * @description:  Draw card  * @param aGuaranteed  Extraordinary guaranteed times , If continuous n-1 I didn't draw the extraordinary , Is the first n Forced acquisition for times  * @param aGetMax  Parameters times How many extraordinary cards can you draw at most at a time ( Limit lucky users ) * @param times  Number of cards drawn by the user  * @return: * @author: Ming * @time: 2022/6/9 */
    private static void drawCard(int aGuaranteed, int aGetMax, int times){
    
        Random random = new Random();
        CardType a = cardTypes.get(" Extraordinary ");
        CardType b = cardTypes.get(" rare ");
        CardType c = cardTypes.get(" Precious ");
        int aGetTimes = 0;
        int bGetTimes = 0;
        int cGetTimes = 0;
        int dGetTimes = 0;
        int notTimes = 0; // The cumulative number of times you didn't win the game 
        // Start to draw cards 
        for (int i = 0; i < times; i++) {
    
            // Random generation 1 To 100 Integer between , Because the probabilities of various cards add up to 100%, Here is to 1～100 The number of indicates the probability range of various card types ,
            // for example ： Extraordinary probability %3, Then the probability range is 1～3, Precious card probability %5, Then the probability range is 4～8, And so on 
            int num = random.nextInt(100)+1;
            if(notTimes == aGuaranteed && aGetTimes < aGetMax){
    
                System.out.println(" The system forces the issuance of extraordinary cards ");
                aGetTimes++;
                notTimes = 0;// Reset 
            }else {
    
                notTimes++;
                if(num <= a.getMax() && aGetTimes < aGetMax){
    
                    System.out.println(" Draw the extraordinary card ");
                    aGetTimes++;
                    notTimes = 0;
                }else if(num <= b.getMax()){
    
                    System.out.println(" Draw a rare card ");
                    bGetTimes++;
                }else if(num <= c.getMax()){
    
                    System.out.println(" Draw a precious card ");
                    cGetTimes++;
                }else{
    
                    System.out.println(" Draw an ordinary card ");
                    dGetTimes++;
                }
            }
        }
        System.out.println(" The number of extraordinary cards drawn this time ："+aGetTimes);
        System.out.println(" The number of rare cards drawn this time ："+bGetTimes);
        System.out.println(" The number of precious cards drawn this time ："+cGetTimes);
        System.out.println(" The number of ordinary cards drawn this time ："+dGetTimes);
    }


    public static void main(String[] args) {
    
        drawCard(20,3,100);
    }

}

test result

The above is a simple implementation , In development , Some cardinalities are read configuration when the server starts , Data is preloaded into memory , for example ： Probability of card type , Card deck, etc , For example, draw an extraordinary card , The system randomly allocates an extraordinary card from memory id To the user . The probability algorithm implemented by Netease is much more complicated , This is just a reflection of my own problems , discuss , Realization ; I hope you can correct me