update usage in main.cpp

main.cpp

 #include <iostream>
+#include<stdio.h>
 #include <vector>
 #include "sorting.h"
 
@@ -7,15 +8,20 @@ using namespace std;
 int main(int argc, char const *argv[]) //main function
 {
 	vector<int> a;
+	int s,e;
 	int num = 0;
-
+	printf("Enter start & end index : ");
+	scanf("%d %d", &s, &e);
 	while (num != -1)
 	{
 		std::cin>>num;
 		if (num != -1)
 		a.push_back(num);
 	}
-	a = sort_custom(a);
+	vector<int> tmp = sort_custom(a,s,e);
+
+	for(int i=s;i<e;i++)
+		a[i]=tmp[i-s];
     for (int i=0;  i <a.size();  i++)
 	{
 		cout<<a[i]<<" ";