Data Structures and Algorithms - Quick Sort

Quicksort (sometimes called partition-exchange sort) is an efficient sorting algorithm, serving as a systematic method for placing the elements of an array in order. Developed by Tony Hoare in 1959(published 1962), it is still a very commonly used algorithm for sorting. When implemented well, it can be about two or three times faster than its main competitors, merge sort and heap sort.
Quicksort is a comparison sort, meaning that it can sort items of any type for which a "less-than" relation (formally, a total order) is defined. In efficient implementations it is not a stable sort, meaning that the relative order of equal sort items is not preserved. Quicksort can operate in-place on an array, requiring small additional amounts of memory to perform the sorting.
Mathematical analysis of quicksort shows that, on average, the algorithm takes O(n log n) comparisons to sort n items. In the worst case, it makes O(n²) comparisons, though this behavior is rare.

It's Work like this :

Code Is :

 

-Vishva Rodrigo-

Data Structures and Algorithms - Selection Sort

Hello Guyz,
Now I'm going to show you How Selection Sort Works.In computer science, selection sort is a sorting algorithm, specifically an in-place comparison sort. It has O(n²) time complexity, making it inefficient on large lists, and generally performs worse than the similar insertion sort. Selection sort is noted for its simplicity, and it has performance advantages over more complicated algorithms in certain situations, particularly where auxiliary memory is limited.
The algorithm divides the input list into two parts: the sublist of items already sorted, which is built up from left to right at the front (left) of the list, and the sublist of items remaining to be sorted that occupy the rest of the list. Initially, the sorted sublist is empty and the unsorted sublist is the entire input list. The algorithm proceeds by finding the smallest (or largest, depending on sorting order) element in the unsorted sublist, exchanging it with the leftmost unsorted element (putting it in sorted order), and moving the sublist boundaries one element to the right.

Time Complexity of Selection Sort is : O(n²)

 

Code is : 

 -Vishva Rodrigo-

Data Structures and Algorithms - Insertion Sort

Hello Guyz,
Now I'm Going to show you How Insertion Sort works.Insertion sort is a simple sorting algorithm that builds the final sorted array (or list) one item at a time. It is much less efficient on large lists than more advanced algorithms such as quick sort, heap sort, or merge sort. However, insertion sort provides several advantages:

• Simple implementation: Bentley shows a three-line C version, and a five-line optimized version.
• Efficient for (quite) small data sets
• More efficient in practice than most other simple quadratic (i.e., O(n²)) algorithms such as selection sort or bubble sort
• Adaptive, i.e., efficient for data sets that are already substantially sorted: the time complexity is O(nk) when each element in the input is no more than k places away from its sorted position
• Stable; i.e., does not change the relative order of elements with equal keys
• In-place; i.e., only requires a constant amount O(1) of additional memory space
• Online; i.e., can sort a list as it receives it

When people manually sort something (for example, a deck of playing cards), most use a method that is similar to insertion sort

Insertion Sort is Work like this :

Code is :

-Vishva Rodrigo-