Write the following. Include a type declaration for each value or function. You

Question

Write the following. Include a type declaration for each value or function. You should not define a function with one word (because there happens to be an identical function built in) or define a value directly (instead of constructing it with, e.g., a list comprehension) A function "duplicates that takes a list and returns true if any two elements in the list are the same. A list of pairs 'rolls' showing all possible rolls of two six-sided dice. A function 'counts' that takes a list and returns a list of pairs, with each pair containing an element and the number of times it appears. A list of pairs 'sums', showing how often each sum appears when rolling two six-sided dice.

Explanation / Answer

import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Test {

   public static void main(String[] args) {

       Test test = new Test();

       //create list having duplicate elements
       List<String> list = Arrays.asList(new String[] {"A","B","C","A"});

       System.out.println("Check duplicacy in list: ");
       System.out.println(test.checkDuplicates(list));
      
       System.out.println("All possible dice rolls are: ");
       test.allPossibleDiceRolls("", 2);
      
       System.out.println("Count digit frequency: ");
       test.countDigitFrequency(new int[] {1,2,3,1,1,1,2,2,3,4,6,5,5,5});
      
       System.out.println("Number appears in dice");
       Map<Integer, Integer> map = test.getDiceMapOfNumberList(new int[] {4,7,8,5});
       Set<Integer> keys = map.keySet();
       for(int key : keys) {
           System.out.println("number " +key+" comes => " + map.get(key) + " times" );
       }

   }

   public <T> boolean checkDuplicates(List<T> list) {

       Set<T> set = new HashSet<T>();
       for(T data : list)
           if(!set.add(data))
               return true;
       return false;

   }

   public void allPossibleDiceRolls(String s, int depth) {
       if(depth == 0)
           System.out.println(s.substring(1));
       else
           for(int i = 1; i <= 6; i++)
               allPossibleDiceRolls(s + "," + i, depth - 1);
   }
  
   public void countDigitFrequency(int x[]) {
HashMap<Integer,Integer>digits=new HashMap<Integer,Integer>();
for (int i : x){
if (digits.containsKey(i)){
digits.put(i, digits.get(i)+1);
} else {
digits.put(i, 1);
}
}
for (int key:digits.keySet()){
System.out.println(key+" comes "+digits.get(key) + " times");
}
}
  
   private int numberPossibilitiesInRollingDices(int numberOfDice, int sum) {
   if (numberOfDice == sum)
   return 1;
   else if (numberOfDice == 0 || sum < numberOfDice)
   return 0;
   else
   return numberPossibilitiesInRollingDices(numberOfDice, sum - 1) +
           numberPossibilitiesInRollingDices(numberOfDice - 1, sum - 1) -
           numberPossibilitiesInRollingDices(numberOfDice - 1, sum - 7);
   }
  
   public Map<Integer, Integer> getDiceMapOfNumberList(int[] numbers) {
       Map<Integer, Integer> diceMap = new HashMap<Integer, Integer>();
       for(int num : numbers) {
           diceMap.put(num,numberPossibilitiesInRollingDices(2, num));
       }
       return diceMap;
   }

}

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