The merge sort algorithm presented below sorts uses the merge method which is partially shown below. Select the condition that would be needed to complete the method so that the elements are sorted in descending order.

private static void merge(int[] first, int[] second, int[] a)
{
int iFirst = 0;
int iSecond = 0;
int j = 0;

while (iFirst

Question

The merge sort algorithm presented below sorts uses the merge method which is partially shown below. Select the condition that would be needed to complete the method so that the elements are sorted in descending order.

private static void merge(int[] first, int[] second, int[] a)
{
   int iFirst = 0;
   int iSecond = 0;
   int j = 0;
 
   while (iFirst < first.length && iSecond < second.length)
   {  
      if (_____________________________)
      {
         a[j] = first[iFirst]; 
         iFirst++;
      }
      else
      {
         a[j] = second[iSecond];
         iSecond++;
      }
      j++;
   }
   // rest of the method follows here
}

BlackTom AI · Accepted Answer

To sort in descending order, always select the larger of the two current elements from the two sorted subarrays during each merge step. 1. Relevant knowledge points and concepts - Merge step of merge sort repeatedly compares the current front elements of two sorted subarrays and copies the appropriate element into the output array. - For descending order, the element chosen at each comparison should be the greater (larger) of the two current elements. - iFirst and iSecond are indices into the two subarrays; comparisons must be between element values, not indices. 2. Complete reasoning process step by step - At the start of each loop iteration we have two candidates: first[iFirst] and second[iSecond]. - To place elements in descending order, test whether the element from the first subarray is greater than the element from the second subarray. - If first[iFirst] > second[iSecond] is true, copy first[iFirst] into a[j] and increment iFirst; otherwise copy second[iSecond] and increment iSecond. - Increment j after placing an element. - When one subarray is exhausted, copy the remaining elements from the other subarray (this is the “rest of the method”). 3. Intermediate steps / example - Example: first = [9, 5, 3], second = [8, 7, 2], a initially empty. - Compare first[0]=9 and second[0]=8 → 9 > 8 true → a[0]=9, iFirst=1, j=1. - Compare first[1]=5 and second[0]=8 → 5 > 8 false → a[1]=8, iSecond=1, j=2. - Compare first[1]=5 and second[1]=7 → 5 > 7 false → a[2]=7, iSecond=2, j=3. - Continue until all elements copied → a = [9,8,7,5,3,2]. 4. Why the correct answer is correct - The condition first[iFirst] > second[iSecond] directly selects the larger current value, ensuring the merged array is built from largest to smallest, which produces a descending order. 5. Why the other options are incorrect - first[iFirst] < second[iSecond] would select the smaller element first, producing ascending order (opposite of required). - iFirst > iSecond and iFirst < iSecond compare indices, not element values; those comparisons do not implement correct ordering logic and are meaningless for ordering values. 6. Conclusion / final confirmation - The correct condition to place in the if statement is: first[iFirst] > second[iSecond]. This matches the provided answer.

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