how does a quick sort work?
时间: 2023-12-04 22:04:33 浏览: 87
Quick sort is a sorting algorithm that works by dividing an array into two smaller sub-arrays around a pivot element, and then recursively sorting the sub-arrays. The steps involved in quick sort are as follows:
1. Choose a pivot element from the array. This element can be chosen randomly or as the first, last or middle element of the array.
2. Partition the array into two sub-arrays, such that all elements smaller than the pivot are in the first sub-array, and all elements larger than the pivot are in the second sub-array.
3. Recursively apply the quick sort algorithm to each sub-array.
4. Concatenate the sorted sub-arrays to obtain the final sorted array.
The partitioning step is the most important part of quick sort. It involves comparing each element of the array to the pivot element, and swapping elements to ensure that all elements smaller than the pivot are to the left of it, and all elements larger than the pivot are to the right of it. This process is repeated until the pivot element is in its final position, and the array is partitioned into two sub-arrays, which can then be sorted recursively.
The efficiency of quick sort depends on the choice of pivot element. In the worst case scenario, when the pivot element is chosen poorly, the algorithm can take O(n^2) time. However, on average, quick sort has a time complexity of O(n log n), which makes it one of the most efficient sorting algorithms.
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