{"id":470,"date":"2023-05-17T11:20:58","date_gmt":"2023-05-17T11:20:58","guid":{"rendered":"https:\/\/vmlogger.com\/algorithms\/?p=470"},"modified":"2023-05-17T11:20:58","modified_gmt":"2023-05-17T11:20:58","slug":"quick-sort-understanding-and-implementing-in-python","status":"publish","type":"post","link":"https:\/\/vmlogger.com\/algorithms\/2023\/05\/17\/quick-sort-understanding-and-implementing-in-python\/","title":{"rendered":"Quick Sort: Understanding and Implementing in Python"},"content":{"rendered":"
Among the various sorting algorithms available, Quick Sort stands out as one of the efficient and widely used sorting algorithms. Although, it can offer a worst case time complexity as In this article, we will dive into the details of the Quick Sort algorithm, understand its workings, and implement it in Python.<\/p>\n Similar to merge sort<\/a>, quick sort is also based on divide-and-conquer<\/a> algorithm principle. It was developed by British computer scientist Tony Hoare<\/a> in 1959. The algorithm’s core idea is to partition the input array into two sub-arrays, where one sub-array contains elements smaller than a chosen pivot, and the other sub-array contains elements greater than the pivot. <\/p>\n This process is repeated recursively on the sub-arrays until the entire array is sorted. This is the reason, quick sort is also known as partition-exchange sorting algorithm. <\/p>\n The partitioning process plays a crucial role in Quick Sort. It determines the pivot element’s correct sorted position and rearranges the array accordingly. Several approaches exist for selecting the pivot, but the most commonly used one is the O(n^2)<\/code> but it offers a best and an average-case time complexity of
O(n log n)<\/code> and performs exceptionally well in practice.
\nOverall, it is slightly faster than merge sort<\/a> and heapsort<\/a> for randomized data, particularly on larger distributions.[3]<\/p>\nIntroduction to Quick Sort<\/h2>\n
The key steps involved in the Quick Sort algorithm are as follows:<\/h4>\n
\n
Partitioning:<\/code> Choose a pivot element from the array. Rearrange the array in such a way that all elements smaller than the pivot are placed before it, and all elements greater than the pivot are placed after it. The pivot element is now in its correct sorted position.\n<\/li>\n
Recursion:<\/code> Apply the partitioning step recursively to the sub-arrays formed on the left and right sides of the pivot until the entire array is sorted. This process is known as the divide-and-conquer approach.\n<\/li>\n
Combining:<\/code> Since the recursion splits the array into smaller sub-arrays, no explicit combining step is necessary. The elements are automatically combined as the recursion unwinds.\n<\/li>\n<\/ol>\n
Understanding the Partitioning Process<\/h2>\n
\"Lomuto partition scheme.\"<\/code><\/p>\n
The
Lomuto partition scheme<\/code> involves the following steps:<\/h4>\n
\n
i<\/code> to keep track of the index where elements smaller than the pivot will be placed. Initially, set i to the first element’s index, which is
0<\/code>.<\/li>\n
i<\/code> and increment
i<\/code> by 1. This ensures that all smaller elements are placed before the pivot.<\/li>\n
i<\/code>. Now, the pivot element is in its final sorted position.<\/li>\n
i<\/code>) are smaller than the pivot, and all elements to the right of the pivot (indices greater than
i<\/code>) are larger than the pivot. This partitioning step ensures that the pivot element is in its correct sorted position while dividing the array into two sub-arrays for further recursion.<\/li>\n<\/ol>\n