Merge pull request deutranium#219 from K-u-n-a-l-c/patch-6

Create README.md HeapSort

Author: codelixir

sortingAlgo/heapSort/README.md

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+# Heap Sort
+Heap sort is one of the sorting algorithms used to arrange a list of elements in order. Heapsort algorithm uses one of the tree concepts called Heap Tree. 
+In this sorting algorithm, we use Max Heap to arrange list of elements in Descending order and Min Heap to arrange list elements in Ascending order.
+There are 2 variations of heap possible
+### MIN HEAP
+* Here the value of parent is always less than the value of its children
+Hence root will be the minimum in the entire heap
+### MAX HEAP
+* Here the value of parent is always more than the value of its children
+Hence root will be the maximum in the entire heap
+
+## Algorithm
+* Step 1 - Construct a Binary Tree with given list of Elements.
+* Step 2 - Transform the Binary Tree into Max Heap.
+* Step 3 - Delete the root element from Max Heap using Heapify method.
+* Step 4 - Put the deleted element into the Sorted list.
+* Step 5 - Repeat the same until Max Heap becomes empty.
+* Step 6 - Display the sorted list.
+
+## Pseudo-code
+```
+heapify(arr , i)
+	leftChild = arr [2*0 + 1];
+	rightChild = arr [2*0 + 2];
+    	maxIndex = max( arr[i], leftChild, rightChild)
+    	if(i != maxIndex)
+          		swap(arr[i], arr[maxIndex])
+  ```
+  ```
+  buildMaxHeap(arr)
+	for(int i = n / 2 - 1; i >= 0; i--)
+     		 heapify(arr, i);
+```
+
+## Complexity
+
+-   Worst case time complexity:  `O(n log n)`
+-   Average case time complexity:  `O(n log n)`
+-   Best case time complexity:  `O(n log n)`
+-   Space complexity:  `O(1)`
+
+## Applications of Heap Sort 
+* K sorted array
+* K largest or smallest elements in an array 
+
+###  Instruction for Running code:
+ - C
+     ```
+     gcc heapSort.c
+     ./a.out
+     ```
+ - Cpp
+
+     ````
+     g++ heapSort.cpp
+     ./a.out
+     ````
+- Java
+
+    ```
+    javac heapSort.java
+    java heapSort.class
+    ```
+- Python
+    ```
+    python3 heapSort.py
+    ```