Add shell sort algorithm

Author: Shradha27

sorting/shell_sort.cpp

@@ -0,0 +1,62 @@
+//
+// C++ implementation of shell sort
+//
+// The All ▲lgorithms Project
+//
+// https://allalgorithms.com/sorting
+// https://github.com/allalgorithms/cpp
+//
+// Contributed by: Shradha Sharma
+// Github: @shradha27
+//
+#include<iostream>
+ 
+using namespace std;
+ 
+// A function implementing Shell sort.
+void ShellSort(int a[], int n)
+{
+int i, j, k, temp;
+// Gap 'i' between index of the element to be compared, initially n/2.
+for(i = n/2; i > 0; i = i/2)
+{
+for(j = i; j < n; j++)
+{
+for(k = j-i; k >= 0; k = k-i)
+{
+// If value at higher index is greater, then break the loop.
+if(a[k+i] >= a[k])
+break;
+// Switch the values otherwise.
+else
+{
+temp = a[k];
+a[k] = a[k+i];
+a[k+i] = temp;
+}
+}
+}
+}
+}
+int main()
+{
+int n, i;
+cout<<"\nEnter the number of data element to be sorted: ";
+cin>>n;
+ 
+int arr[n];
+for(i = 0; i < n; i++)
+{
+cout<<"Enter element "<<i+1<<": ";
+cin>>arr[i];
+}
+ 
+ShellSort(arr, n);
+ 
+// Printing the sorted data.
+cout<<"\nSorted Data ";
+for (i = 0; i < n; i++)
+cout<<"->"<<arr[i];
+ 
+return 0;
+}