Question

Java 176

Lottery Program in Word.

Using ArrayLists to Simulate a Lottery Program

Simulate a Lottery Drawing by choosing 7 numbers at random from a pool containing 30 numbers

Each time a number is selected, it is recorded and removed from the pool

The pool values are 00 to 29 inclusive

1. Your program must output each selected number from the drawing using a two-digit format. For Example, the number 2 would be represented by 02 on the “Picked” line.
2. The numbers drawn cannot repeat
3. Sort the picked numbers before printing them to the console
4. Show the initial and remaining pool
5. Your output must match as closely as possible to what is shown below

Example Output:

Initial Pool: [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]

Picked: {01,06,09,19,25,26,27}

Remaining:[0,2,3,4,5,7,9,10,11,12,13,14,15,16,17,18,20,21,22,23,24,28,29]

Algorithm

1. Create two ArrayLists of type Integer called pool and pick
2. Create a Random Number to represent the number chosen, it will represent the index of the number chosen
3. Create the pool ArrayList by using a loop going from 0 to <30. Print the pool ArrayList Out
4. Choose 7 numbers at random, remove them from the pool ArrayList and place them in the picked ArrayList.
5. Use Collections.sort(pick) to sort the pick ArrayList<Integer>
6. Print the pick ArrayList out but add an additional 0 in the front if it is one digit. Example, change 2 to 02.

Print out the remaining pool after the numbers are picked

Answer 1

Implementation in JAVA:

// import some neccessary classes
import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;

public class Lottery {
  
// driver method
   public static void main(String[] args) {
      
//       declare arraylist initial
ArrayList<Integer> initial= new ArrayList<Integer>();

// adding elements
for(int i=0;i<=29;i++) {
   initial.add(i);
}
      
// printing initial
System.out.println("Initial pool : "+initial);

// declare picked arraylist
ArrayList<Integer> picked= new ArrayList<Integer>();

// for picking 7 random elements
for(int i=0;i<7;i++) {
     
//   call method which is defined below for generating random numbers
   int random=getRandomNumberUsingNextInt(0,29);
     
//   check wheather it is picked earlier if yes then generate random no. again
   while(!check(initial,random)) {
       random=getRandomNumberUsingNextInt(0,29);
   }
     
//   removing picked no. form initial list
   for(int j=0;j<initial.size();j++) {
         
       if(initial.get(j)==random) {
           initial.remove(j);
       }
         
   }
     
//   add random to picked list
   picked.add(random);
     
}

// sort picked list by Collections
Collections.sort(picked);


// print picked in 2 digit format
System.out.print("Picked : {");
         
for(int i=0;i<picked.size();i++) {
     
   if(i==picked.size()-1) {
       System.out.print(String.format("%02d" , picked.get(i)));
   }
   else
   System.out.print(String.format("%02d" , picked.get(i))+", ");
}
System.out.println("}");


// print remaining pool
System.out.println("Remaiming pool : "+initial);

      
      
      
   }
  
//   method for generating random no. with in range
   public static int getRandomNumberUsingNextInt(int min, int max) {
   Random random = new Random();
   return random.nextInt(max - min) + min;
   }
  
//   method for checking wheather num is in list or not
   public static boolean check(ArrayList<Integer> list, int num) {
      
       for(int i=0;i<list.size();i++) {
           if(list.get(i)==num) {
               return true;
           }
       }
      
       return false;
      
   }

}

SAMPLE OUTPUTS:

1:

2:

Time complexity is high so you have to wait for a second for output

If you have any doubt regarding this question please ask me in comments

// THANK YOU:-)