add basic implementation

main.cpp

 #include<iostream>
 #include<vector>
 #include "sorting.h"
+#include "sorting.cpp"
 using namespace std;
 int main(){
 int n;

sorting.cpp

+#include<iostream>
+#include<vector>
+#include "sorting.h"
+using namespace std;
+
+vector<int> sort_custom(vector<int> c){
+  bool pass = false; //have we passed through the cay without a swap?
+  int temp;
+
+  while (!pass){
+    pass = true;
+    for (int i=0; i<c.size()-1; i++){
+      if (c[i] > c[i+1]){
+        pass = false;
+        temp = c[i];
+        c[i] = c[i+1];
+        c[i+1] = temp;
+      }
+    }
+  }
+  return c;
+}
+

sorting.h

 #include<iostream>
 #include<vector>
 using namespace std;
-vector<int> sort_custom(vector<int>);
+vector<int> sort_custom(vector<int>d);