Question

   Method sandwiched returns true if num is in the element before and after
           an element that is not equal to num

          sandwiched([4,5,4,6,7,3], 4) returns true
          sandwiched([2,1,2], 2) returns true
          sandwiched([3,3,3], 3) returns false
          sandwiched([4,5,6,4], 4) returns false
           sandwiched([1,1,2,3,1,4,1], 1) returns true
          @param nums Integer ArrayList
           @param num integer
          @return true if a single number is between elements equal to num
      */
      public static boolean sandwiched(ArrayList<Integer> nums, int num)
      {
          return false;
      }//end sandwiched

Answer 1

Hi,

Hope you are doing fine. I have coded the question in java keeping all the requirements in mind. I have tested the output with all the given inputs and the result seems positive. The code has been clearly explained using comments that have been highlighted in bold.

Program:

import java.util.ArrayList;

public class Sandwich {
  
   //method as per the question
   public static boolean sandwiched(ArrayList<Integer> nums, int num)
{
       //we traverse through the list using i
       //note that we only traverse up to size-2 elements as the elements beyond that cannot be sandwiched
       for(int i=0;i<nums.size()-2;i++)
       {
           //if the number in the list is equal to num and if it is not nums.size()-2
           if(nums.get(i)==num && i!=nums.size()-2)
           {
               //if the next number in list is not equal to current number and the number next to the next number is same as current number
               if(nums.get(i)!=nums.get(i+1) && nums.get(i)==nums.get(i+2))
                   //return True
                   return true;
           }
       }
       //if no numbers are sandwiched
return false;
}//end sandwiched

   //Main method is only used for testing
   public static void main(String[] args) {
      
       // Testing the method using the call sandwiched([1,1,2,3,1,4,1], 1). It must return true as 4 is sandwiched between 1's at the end of the list
       ArrayList<Integer> test=new ArrayList<Integer>();
       test.add(1);
       test.add(1);
       test.add(2);
       test.add(3);
       test.add(1);
       test.add(4);
       test.add(1);
       boolean result=sandwiched(test, 1);
       System.out.println(result);
      
       // Testing the method using the call sandwiched([3,3,3], 3). It must return false as all elements are equal
       ArrayList<Integer> test1=new ArrayList<Integer>();
       test1.add(3);
       test1.add(3);
       test1.add(3);
       result=sandwiched(test1, 3);
       System.out.println(result);

   }

}

Executable code snippet:

Output: