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In: Computer Science

What type of algorithm is the Quicksort algorithm if it has random pivots?

What type of algorithm is the Quicksort algorithm if it has random pivots?

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Expert Solution

Lomuto's partition scheme or Hoare's partition scheme algorithm is use for the Quicksort algorithm if it has random pivots. In general, quicksort is a divide-and-conquer algorithm. It works by selecting a 'pivot' element from the array and partitioning the other elements into two sub-arrays.

Lomuto's Partition Scheme Algorithm using Random Pivots:

partition(arr[], lo, hi) 
    pivot = arr[hi]
    i = lo     
    for j := lo to hi – 1 do
        if arr[j] <= pivot then
            swap arr[i] with arr[j]
            i = i + 1
    swap arr[i] with arr[hi]
    return i

partition_r(arr[], lo, hi)
    r = Random Number from lo to hi
    Swap arr[r] and arr[hi]
    return partition(arr, lo, hi)

quicksort(arr[], lo, hi)
    if lo < hi
        p = partition_r(arr, lo, hi)
        quicksort(arr, lo , p-1)
        quicksort(arr, p+1, hi)

Lomuto's partition scheme is easy to implement as compared to Hoare scheme.


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