add makefile

Makefile

+
+all: main
+main: main.o sorting.o
+	g++ main.o sorting.o -o main
+main.o: sorting.h 
+sorting.o: sorting.cpp sorting.h
+	g++ -c sorting.cpp sorting.h

main.cpp

 #include<iostream>
 #include<vector>
 #include "sorting.h"
-#include "sorting.cpp"
 using namespace std;
 int main(){
 int n;
@@ -12,7 +11,7 @@ int x;cin>>x;
 a.push_back(x);
 }
 vector<int> b=sort_custom(a);
-for(vector<int>::iterator it=a.begin() ; it!=a.end() ; ++it){
+for(vector<int>::iterator it=b.begin() ; it!=b.end() ; ++it){
 cout<< *it<<" ";
 }
 cout<<endl;