The quicksort algorithm has a worst-case running time of O(n^2) on an input array of *n* numbers, and worst case happens when the array is sorted in descending order. Despite a worst-case running time, quicksort is often the best practical choice for sorting. Its average expected running time is O(n log n), and it has an advantage of sorting in place.

# Algorithms, Merge-Sort

Merge sort is another sorting algorithm that applies the divide-and-conquer approach, where the problem is divided into sub-problems recursively. Keep dividing until the subproblem becomes primitive. After that, the results of the divisions are combined and formed the result for the upper caller and so on.

# Algorithms, Medians and Order Statistics

The *i* th **order statistic* of a set of *n* elements is the *i* th smallest element. Simply saying the *minimum* of a set of elements is the first order statistic (i = 1) and *maximum* is the *n*th order statistic (i = n). *Median* is the informally considered as a “halfway point” of the set.

# Algorithms, Insertion Sort

**Insertion sort**, which is an efficient algorithm for sorting a small number of elements. Insertion sort works the way many people do it by hand while playing a card game (*Though personally i would not sort the cards while playing, because there are too many skill-full guys, who may take an advantage of it*)

# Algorithms, Heap Sort

The **(binary) heap** data structure is an array object that we can view as a nearly complete binary tree. A complete binary tree is a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possible.

# Algorithms, Divide-and-conquer

In a paradigm of divide-and-conquer we solve the problem recursively, applying three basic steps at each level of the recursion:

# Hackerrank, Swap Nodes[Algo]

It has been such a long time since I didn’t work on graphs and trees. Here it is I’m back. This task is quite a simple one even though it is assigned a medium level of difficulty. The original task definition is given hackerrank.

# Hackerrank, Minimum Loss

Here another weird problem given by hackerrank, though It was fun to solve this problem as well. This problem is good example of importance of understanding the given task. Sometimes it may have a straight logic from the definition of the task. Why is the Lauren wants to sell the houses and make a loss, not profit. Isn’t the profit is main purpose of any business, so guys be careful when reading the definition of the task.

# Hackerrank, Nimble Game

Original definition of the problem is given at hackerrank. In order to avoid copyright related issues, I would like to not keep the definition of the problem in here.

# Hackerrank, 3D Surface Area

Original definition of the problem is given at hackerrank. In order to avoid copyright related issues, I would like to not keep the definition of the problem in here.