# What is the quicksort algorithm?

## What is the quicksort algorithm?

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, according to whether they are less than or greater than the pivot. The sub-arrays are then sorted recursively.

**How does smooth sort work?**

Smooth sort is an enhanced version of heap sort. The advantage is that smooth sort takes O(N) time with already sorted data and, when the degree of disorder grows, the transition from O(N) to O(N log N) is smooth (hence the name). That is, smooth sort takes nearly O(N) when the data are nearly sorted.

### How does heapsort work?

Suppose an array consists of N distinct elements in memory, then the heap sort algorithm works as follows: To begin with, a heap is built by moving the elements to its proper position within the array. In the second phase, the root element is eliminated from the heap by moving it to the end of the array.

**What is Quicksort algorithm with example?**

In simple QuickSort algorithm, we select an element as pivot, partition the array around pivot and recur for subarrays on left and right of pivot. Consider an array which has many redundant elements. For example, {1, 4, 2, 4, 2, 4, 1, 2, 4, 1, 2, 2, 2, 2, 4, 1, 4, 4, 4}.

## What is Quicksort explain with example?

Quick Sort is a sorting algorithm, which is commonly used in computer science. Quick Sort is a divide and conquer algorithm. It creates two empty arrays to hold elements less than the pivot value and elements greater than the pivot value, and then recursively sort the sub arrays.

**Which sorting algorithm is worst?**

Bogosort The universally-acclaimed worst sorting algorithm is Bogosort, sometimes called Monkey Sort or Random Sort, for reasons we’ll see shortly. Bogosort develops from the idea that, in probability theory, if a certain phenomenon is possible, then it will eventually happen.

### Which sorting algorithm is best for sorted array?

insertion sort

When the array is almost sorted, insertion sort can be preferred. When order of input is not known, merge sort is preferred as it has worst case time complexity of nlogn and it is stable as well.

**How do you use radix sort?**

Radix sort works by sorting each digit from least significant digit to most significant digit. So in base 10 (the decimal system), radix sort would sort by the digits in the 1’s place, then the 10’s place, and so on. To do this, radix sort uses counting sort as a subroutine to sort the digits in each place value.

## How do you do insertion sort?

Working of Insertion Sort

- The first element in the array is assumed to be sorted. Take the second element and store it separately in key .
- Now, the first two elements are sorted. Take the third element and compare it with the elements on the left of it.
- Similarly, place every unsorted element at its correct position.

**Is heapsort the best?**

The most direct competitor of quicksort is heapsort. Heapsort’s worst-case running time is always O(n log n). But, heapsort is assumed to be on average somewhat slower than standard in-place quicksort.

### Is heapsort stable?

No

Heapsort/Stable

Heap sort is not stable because operations in the heap can change the relative order of equivalent keys. The binary heap can be represented using array-based methods to reduce space and memory usage. Heap sort is an in-place algorithm, where inputs are overwritten using no extra data structures at runtime.

**What is the difference between heapsort and smoothsort?**

Whereas heapsort uses an implicit tree structure on the array in which a parent node always come before its descendants, so that the initial element is the root of the tree, smoothsort uses an implicit tree structure where a parent node always comes after its descendants.

## What kind of traversal is used in smoothsort?

Smoothsort uses a different mapping, a bottom-up depth-first post-order traversal. A left child is followed by the subtree rooted at its sibling, and a right child is followed by its parent. Every element has a well-defined height above the leaves, and every non-leaf element has its children earlier in the array.

**When did Edsger Dijkstra invent the algorithm smoothsort?**

In computer science, smoothsort is a comparison-based sorting algorithm. A variant of heapsort, it was invented and published by Edsger Dijkstra in 1981. Like heapsort, smoothsort is an in-place algorithm with an upper bound of O ( n log n ), but it is not a stable sort.

### How is smoothsort related to Fibonacci numbers?

Dijkstra’s formulation of smoothsort uses a different rule, in which sibling subtrees never have equal sizes (except when both are 1), and the sizes of all subtrees are among a set of values that he calls Leonardo numbers (they are closely related to Fibonacci numbers ).