From b06bbf4dc6c46a3284d7852bb570438384eef4ef Mon Sep 17 00:00:00 2001
From: Ayaan Khan <ayaankhan98@gmail.com>
Date: Sat, 20 Jun 2020 21:00:52 +0530
Subject: [PATCH] Fixed Bug [munmap_chunck() core dumped]

---
 sorting/merge_sort.cpp | 72 +++++++++++++++++++++++++++++++-----------
 1 file changed, 54 insertions(+), 18 deletions(-)

diff --git a/sorting/merge_sort.cpp b/sorting/merge_sort.cpp
index 82ab869cd..c28a28fe6 100644
--- a/sorting/merge_sort.cpp
+++ b/sorting/merge_sort.cpp
@@ -1,5 +1,36 @@
+/**
+ *  \addtogroup sorting Sorting Algorithms
+ *  @file{
+ *  \file
+ *  \breif [Merege Sort Algorithm
+ *  (MEREGE SORT)](https://en.wikipedia.org/wiki/Merge_sort) implementation
+ *
+ *  \author [Ayaan Khan] (http://github.com/ayaankhan98)
+ *
+ *  Merge Sort is an efficient, general purpose, comparison
+ *  based sorting algorithm.
+ *  Merge Sort is a divide and conquer algorithm
+ *  
+ */
+
 #include <iostream>
 
+/**
+ *
+ * The merge() function is used for merging two halves. 
+ * The merge(arr, l, m, r) is key process that assumes that 
+ * arr[l..m] and arr[m+1..r] are sorted and merges the two 
+ * sorted sub-arrays into one.
+ *
+ * @param arr[] is the array with two halves one is arr[l...m] and
+ * other is arr[m+1...l]
+ * @param l is the left index of first half array
+ * @param m is the end index of right index of first half array
+ * 
+ * (The second array starts form m+1 and goes till l)
+ * 
+ * @param l is the end index of right index of second half array
+ */
 void merge(int arr[], int l, int m, int r) {
     int i, j, k;
     int n1 = m - l + 1;
@@ -40,42 +71,47 @@ void merge(int arr[], int l, int m, int r) {
     delete[] R;
 }
 
+/**
+ * Merge sort is a divide and conquer algorithm, it divides the
+ * input array into two halves and calls itself for the two halves
+ * and then calls merge() to merge the two halves
+ *
+ * @param arr[] the array which is to be sorted
+ * @param l define the left index of array
+ * @param r defines the right index of array
+ *
+ */
 void mergeSort(int arr[], int l, int r) {
     if (l < r) {
         int m = l + (r - l) / 2;
-
         mergeSort(arr, l, m);
         mergeSort(arr, m + 1, r);
-
         merge(arr, l, m, r);
     }
 }
 
-void show(int A[], int size) {
-    int i;
-    for (i = 0; i < size; i++) std::cout << A[i] << "\n";
+/**
+ * A simple utility function used to print the array after
+ * sorting
+ */
+void show(int arr[], int size) {
+    for (int i = 0; i < size; i++)  std::cout << arr[i] << " ";
+    std::cout << "\n";
 }
 
+/** Main function */
 int main() {
     int size;
-    std::cout << "\nEnter the number of elements : ";
-
+    std::cout << "Enter the number of elements : ";
     std::cin >> size;
-
     int *arr = new int[size];
-
-    std::cout << "\nEnter the unsorted elements : ";
-
+    std::cout << "Enter the unsorted elements : ";
     for (int i = 0; i < size; ++i) {
-        std::cout << "\n";
         std::cin >> arr[i];
     }
-
-    mergeSort(arr, 0, size);
-
-    std::cout << "Sorted array\n";
-    show(arr, size);
-
+    mergeSort(arr, 0, size-1);
+    std::cout << "Sorted array : ";
+    show(arr, size-1);
     delete[] arr;
     return 0;
 }