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forsvarir
forsvarir
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If in MedianOf3 method: //swap pivot element to the second to last position

swap(arr, middle, end-1)

//swap pivot element to the second to last position

swap(arr, middle, end-1)

Then in the partition method, before return leftPtrleftPtr, it needs to swap the the pivot from second to last position back to the leftPtrleftPtr position.

Swap(arr, leftPtr, end-1);

swap(arr, leftPtr, end-1);

After switching it back, the pivot element at that position will not change any more. It is the final position for that element.

So quicksort(arr, beginning, partition)quicksort(arr, beginning, partition) can be changed to quicksort(arr, beginning, partition -1 )quicksort(arr, beginning, partition -1 ) because the element at partition position will not change any more. It doesn't need to sort that element

This method is explained in the Robert Lafore's Data Structures and Algorithms in Java book.

If in MedianOf3 method: //swap pivot element to the second to last position

swap(arr, middle, end-1)

Then in the partition method, before return leftPtr, it needs to swap the the pivot from second to last position back to the leftPtr position.

Swap(arr, leftPtr, end-1);

After switching it back, the pivot element at that position will not change any more. It is the final position for that element.

So quicksort(arr, beginning, partition) can be changed to quicksort(arr, beginning, partition -1 ) because the element at partition position will not change any more. It doesn't need to sort that element

This method is explained in the Robert Lafore's Data Structures and Algorithms in Java book.

If in MedianOf3 method:

//swap pivot element to the second to last position

swap(arr, middle, end-1)

Then in the partition method, before return leftPtr, it needs to swap the the pivot from second to last position back to the leftPtr position.

swap(arr, leftPtr, end-1);

After switching it back, the pivot element at that position will not change any more. It is the final position for that element.

So quicksort(arr, beginning, partition) can be changed to quicksort(arr, beginning, partition -1 ) because the element at partition position will not change any more. It doesn't need to sort that element

This method is explained in the Robert Lafore's Data Structures and Algorithms in Java book.

deleted 1 character in body
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yilee
yilee
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If usesin MedianOf3 method: swap(arr, middle, end-1) //swap pivot element to the second to last position

thenswap(arr, middle, end-1)

Then in the partition method, before return leftPtr, it needs to swap the the pivot from second to last position back to the leftPtr position. Swap

Swap(arr, leftPtr, end-1);

After switching it back, the pivot element at that position will not change any more. It is the final position for that element.

So quicksort(arr, beginning, partition) can be changed to quicksort(arr, beginning, partition -1 ) because the element at partition position will not change any more. It doesn't need to sort that element

This method is explained in the Robert Lafore's Data Structures and Algorithms in Java book.

If uses MedianOf3 method: swap(arr, middle, end-1) //swap pivot element to the second to last position

then in the partition method, before return leftPtr, it needs to swap the the pivot from second to last position back to the leftPtr position. Swap(arr, leftPtr, end-1);

After switching it back, the pivot element at that position will not change any more. It is the final position for that element.

So quicksort(arr, beginning, partition) can be changed to quicksort(arr, beginning, partition -1 ) because the element at partition position will not change any more. It doesn't need to sort that element

This method is explained in the Robert Lafore's Data Structures and Algorithms in Java book.

If in MedianOf3 method: //swap pivot element to the second to last position

swap(arr, middle, end-1)

Then in the partition method, before return leftPtr, it needs to swap the the pivot from second to last position back to the leftPtr position.

Swap(arr, leftPtr, end-1);

After switching it back, the pivot element at that position will not change any more. It is the final position for that element.

So quicksort(arr, beginning, partition) can be changed to quicksort(arr, beginning, partition -1 ) because the element at partition position will not change any more. It doesn't need to sort that element

This method is explained in the Robert Lafore's Data Structures and Algorithms in Java book.

Source Link
yilee
yilee
  • 1
  • 1

If uses MedianOf3 method: swap(arr, middle, end-1) //swap pivot element to the second to last position

then in the partition method, before return leftPtr, it needs to swap the the pivot from second to last position back to the leftPtr position. Swap(arr, leftPtr, end-1);

After switching it back, the pivot element at that position will not change any more. It is the final position for that element.

So quicksort(arr, beginning, partition) can be changed to quicksort(arr, beginning, partition -1 ) because the element at partition position will not change any more. It doesn't need to sort that element

This method is explained in the Robert Lafore's Data Structures and Algorithms in Java book.