Create merge_sort.cpp

cpp_programming/merge_sort.cpp

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+// Merge Sort
+
+/*  About Merge Sort
+
+Merge sort is a sorting technique based on divide and conquer technique. With worst-case time complexity being Ο(n log n), it is one of the most respected algorithms.
+
+Merge sort first divides the array into equal halves and then combines them in a sorted manner.
+
+*/
+
+
+#include<bits/stdc++.h>
+using namespace std;
+
+void merge(int *,int, int , int );
+
+void merge_sort(int *arr, int low, int high)
+{
+    int mid;
+    if (low < high)
+    {
+
+        //divide the array at mid and sort independently using merge sort
+        mid=(low+high)/2;
+        merge_sort(arr,low,mid);
+        merge_sort(arr,mid+1,high);
+
+        //merge or conquer sorted arrays
+        merge(arr,low,high,mid);
+
+    }
+}
+
+// Merge sort 
+
+void merge(int *arr, int low, int high, int mid)
+{
+    int i, j, k, c[50];
+    i = low;
+    k = low;
+    j = mid + 1;
+    while (i <= mid && j <= high) {
+        if (arr[i] < arr[j]) {
+            c[k] = arr[i];
+            k++;
+            i++;
+        }
+        else  {
+            c[k] = arr[j];
+            k++;
+            j++;
+        }
+    }
+    while (i <= mid) {
+        c[k] = arr[i];
+        k++;
+        i++;
+    }
+    while (j <= high) {
+        c[k] = arr[j];
+        k++;
+        j++;
+    }
+    for (i = low; i < k; i++)  {
+        arr[i] = c[i];
+    }
+}
+
+// read input array and call mergesort
+
+int main()
+{
+    int arr[30], num;
+
+	cout<<"Enter number of elements to be sorted: ";
+    cin>>num;
+    cout<<"Enter "<<num<<" elements to be sorted: ";
+
+	for (int i = 0; i < num; i++)
+	{
+		cin>>arr[i];
+    }
+
+    merge_sort(arr, 0, num-1);
+
+	cout<<"Sorted array\n";
+    for (int i = 0; i < num; i++)
+    {
+        cout<<arr[i]<<"\t";
+    }
+}