Question

implement and test several recursive methods below. Test all these in the same program. Keep adding methods and testing until all are working.（java）

1.A recursive method to find the sum of all elements of an integer array. The method should have 2 parameters. The array and where to start in the array. Example of initial call:

int sum = sumOfValues(array, 0);

2.A recursive method to find the largest element in an integer array. The method should have 2 parameters as in question1. [Hint: Find the largest in a subset containing all but the first element. Then return the larger of these]

Answer 1

package mis;

public class RecursiveSumTest {
   static int largest=-1;
   public static int sumOfValues(int ar[],int s){
       if(s<0 || s>=ar.length) //if invalid index return 0
           return 0;
       else{
           return ar[s]+sumOfValues(ar,s+1); //else return sum of current element
           //and recursively call for next element of array
       }
   }
   public static int findLargest(int ar[],int s){
       if(s<0 || s>=ar.length) //if invalid index return 0
           return 0;
       else{
           //return maximum of both current element and
           //recursively next element of array
           return Integer.max(ar[s],findLargest(ar,s+1));
       }
   }

   //driver program to test
   public static void main(String[] args) {
      
       int ar[]={1,3,7,2,3};
       int sum=sumOfValues(ar,1);
       System.out.println(sum);
       int largets=findLargest(ar,0);
       System.out.println(largets);
       ar=new int[]{9,34,7,2,3};
       sum=sumOfValues(ar,4);
       System.out.println(sum);
       largets=findLargest(ar,3);
       System.out.println(largets);
   }
  

}

output

15
7
3
3