Java Lottery algorithm

1. Algorithm Analysis

The prizes are divided according to probabilities, each interval represents a prize, and then a random number is taken, and a counter-check falls on that interval, which is the prize drawn.

2. Code

Core algorithms

public class Arithmetic {//magnification private static final int mulriple = 1000000;        public int Pay (list<prize> prizes) {int lastscope = 0;        Shuffle, disrupt prize order collections.shuffle (prizes);        Map<integer, int[]> prizescopes = new Hashmap<integer, int[]> ();        Map<integer, integer> prizequantity = new Hashmap<integer, integer> ();            for (Prize prize:prizes) {int prizeid = Prize.getprizeid ();            Divide the interval int currentscope = Lastscope + prize.getprobability (). Multiply (new BigDecimal (Mulriple)). Intvalue ();            Prizescopes.put (Prizeid, new int[] {lastscope + 1, currentscope});            Prizequantity.put (Prizeid, prize.getquantity ());        Lastscope = CurrentScope;        }//Get a random number between 1-1000000 int luckynumber = new Random (). Nextint (Mulriple);        int Luckyprizeid = 0;         Find the interval of the random number if ((Null! = prizescopes) &&!prizescopes.isempty ()) {   Set<entry<integer, int[]>> entrysets = Prizescopes.entryset ();                For (Map.entry<integer, int[]> m:entrysets) {int key = M.getkey (); if (Luckynumber >= m.getvalue () [0] && luckynumber <= m.getvalue () [1] && prizequantity.get (key)                    > 0) {luckyprizeid = key;                Break    }}} if (Luckyprizeid > 0) {//prize inventory minus one} return Luckyprizeid; }}

Prize Bean

public class Prize {    /**     * Prizes only marked */    private Integer Prizeid;    /**     * Winning probability */    private BigDecimal probability;    /**     * Prize number */    private Integer quantity;    Public Integer Getprizeid () {        return prizeid;    }    public void Setprizeid (Integer prizeid) {        This.prizeid = Prizeid;    }    Public BigDecimal getprobability () {        return probability;    }    public void setprobability (BigDecimal probability) {        this.probability = probability;    }    Public Integer getquantity () {        return quantity;    }    public void setquantity (Integer quantity) {        this.quantity = quantity;    }}

3. Testing

Prize1 Probability: 5%

Prize2 probability : 10%

Prize3 probability : 15%

Prize4 probability : 20%

Prize5 probability : 50%

public class Test {public static void main (string[] args) {list<prize> prizes = new ARRAYLIST&LT;PRIZE&G        t; ();        Prize prize1 = new Prize ();        Prize1.setprizeid (1);        Prize1.setprobability (New BigDecimal (0.05));        Prize1.setquantity (1);        Prizes.add (PRIZE1);        Prize prize2 = new Prize ();        Prize2.setprizeid (2);        Prize2.setprobability (New BigDecimal (0.10));        Prize2.setquantity (10);        Prizes.add (PRIZE2);        Prize prize3 = new Prize ();        Prize3.setprizeid (3);        Prize3.setprobability (New BigDecimal (0.15));        Prize3.setquantity (20);        Prizes.add (PRIZE3);        Prize prize4 = new Prize ();        Prize4.setprizeid (4);        Prize4.setprobability (New BigDecimal (0.20));        Prize4.setquantity (50);        Prizes.add (PRIZE4);        Prize prize5 = new Prize ();        Prize5.setprizeid (5);        Prize5.setprobability (New BigDecimal (0.50));        Prize5.setquantity (200);   Prizes.add (PRIZE5);     int prize1gettimes = 0;        int prize2gettimes = 0;        int prize3gettimes = 0;        int prize4gettimes = 0;        int prize5gettimes = 0;        Arithmetic arithmetic = new arithmetic ();        int times = 1000;            for (int i = 0; I < times; i++) {int prizeid = Arithmetic.pay (prizes);                    Switch (Prizeid) {case 1:prize1gettimes++;                Break                    Case 2:prize2gettimes++;                Break                    Case 3:prize3gettimes++;                Break                    Case 4:prize4gettimes++;                Break                    Case 5:prize5gettimes++;            Break        }} System.out.println ("Number of draws" + times);        System.out.println ("Prize1 winning times" + Prize1gettimes);        System.out.println ("Prize2 winning times" + Prize2gettimes); System.out.println ("Prize3 Winning Times"+ prize3gettimes);        System.out.println ("Prize4 winning times" + Prize4gettimes);    System.out.println ("Prize5 winning times" + Prize5gettimes); }}

Results:

Through 1000 extraction, we see that the accuracy of the algorithm is still very high.

Java Lottery algorithm