Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements and swaps them if they are in the wrong order. The pass through the list is repeated until the list is sorted. The algorithm, which is a comparison sort, is named for the way smaller or larger elements "bubble" to the top of the list.
The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending
order) from unsorted part and putting it at the beginning. The algorithm maintains two subarrays in a given
array.
1) The subarray which is already sorted.
2) Remaining subarray which is unsorted.
In every iteration of selection sort, the minimum element (considering ascending order) from the unsorted
subarray is picked and moved to the sorted subarray.
Insertion sort is a simple sorting algorithm that works similar to the way you sort playing cards in your hands. The array is virtually split into a sorted and an unsorted part. Values from the unsorted part are picked and placed at the correct position in the sorted part.
Like Merge Sort, QuickSort is a Divide and Conquer algorithm. It picks an element as pivot and partitions
the given array around the picked pivot. There are many different versions of quickSort that pick pivot in
different ways.
1) Always pick first element as pivot.
2) Always pick last element as pivot.
3) Pick a random element as pivot.
4) Pick median as pivot.
The key process in quickSort is partition(). Target of partitions is, given an array and an element x of
array as pivot, put x at its correct position in sorted array and put all smaller elements (smaller than x)
before x, and put all greater elements (greater than x) after x. All this should be done in linear time.
heapsort is a comparison-based sorting algorithm. Heapsort can be thought of as an improved selection sort: like selection sort, heapsort divides its input into a sorted and an unsorted region, and it iteratively shrinks the unsorted region by extracting the largest element from it and inserting it into the sorted region. Unlike selection sort, heapsort does not waste time with a linear-time scan of the unsorted region; rather, heap sort maintains the unsorted region in a heap data structure to more quickly find the largest element in each step. Although somewhat slower in practice on most machines than a well-implemented quicksort, it has the advantage of a more favorable worst-case O(n log n) runtime. Heapsort is an in-place algorithm, but it is not a stable sort.