change implementation to merge-sort

Makefile

+CC = g++
+
+all: main.o sorting.o
+	g++ main.o sorting.o -o main
+
+main.o: main.cpp sorting.h
+	g++ -I . -c main.cpp
+    
+sorting.o: sorting.cpp sorting.h
+	g++ -I . -c sorting.cpp
+	
+clean:
+	rm -rf *.o

main.cpp

@@ -3,34 +3,24 @@
 #include "sorting.h"
 
 using namespace std;
-
-void bubbleSort(vector<int>& a);
-
-void printVector(vector<int> a);
+vector<int> sort_custom(vector<int>);
 
 int main(int argc, char const *argv[])
 {
 	vector<int> a;
 	int num = 0;
+
 	while (num != -1)
 	{
 		std::cin>>num;
 		if (num != -1)
-		//add elements to the vector container
 		a.push_back(num);
 	}
-	//printVector(a);	
-	bubbleSort(a);
 
-	printVector(a);
-
-}
-
-
-void printVector(vector<int> a)
-{
-	for (int i=0;  i <a.size();  i++) 
+	a = sort_custom(a);
+    for (int i=0;  i <a.size();  i++) 
 	{
 		cout<<a[i]<<" ";
 	}
 }
+

sorting.cpp

-
+#include <iostream>
+#include <vector>
 
 using namespace std;
-#include <vector>
-void bubbleSort(vector<int>& a)
+
+vector<int> merge(vector<int> left, vector<int> right)
 {
-      bool swapp = true;
-      while(swapp){
-        swapp = false;
-        for (size_t i = 0; i < a.size()-1; i++) {
-            if (a[i]>a[i+1] ){
-                a[i] += a[i+1];
-                a[i+1] = a[i] - a[i+1];
-                a[i] -=a[i+1];
-                swapp = true;
-            }
-        }
-    }
-     // return a;	
+   vector<int> result;
+   while ((int)left.size() > 0 || (int)right.size() > 0) {
+      if ((int)left.size() > 0 && (int)right.size() > 0) {
+         if ((int)left.front() <= (int)right.front()) {
+            result.push_back((int)left.front());
+            left.erase(left.begin());
+         } 
+   else {
+            result.push_back((int)right.front());
+            right.erase(right.begin());
+         }
+      }  else if ((int)left.size() > 0) {
+            for (int i = 0; i < (int)left.size(); i++)
+               result.push_back(left[i]);
+            break;
+      }  else if ((int)right.size() > 0) {
+            for (int i = 0; i < (int)right.size(); i++)
+               result.push_back(right[i]);
+            break;
+      }
+   }
+   return result;
 }
+
+vector<int> sort_custom(vector<int> m)
+{
+   if (m.size() <= 1)
+      return m;
+ 
+   vector<int> left, right, result;
+   int middle = ((int)m.size()+ 1) / 2;
+ 
+   for (int i = 0; i < middle; i++) {
+      left.push_back(m[i]);
+   }
+
+   for (int i = middle; i < (int)m.size(); i++) {
+      right.push_back(m[i]);
+   }
+ 
+   left = sort_custom(left);
+   right = sort_custom(right);
+   result = merge(left, right);
+ 
+   return result;
+}
+

sorting.h

 using namespace std;
-void bubbleSort(vector<int>& a);
-void printVector(vector<int> a);
+vector<int> sort_custom(vector<int>);