update merge-sort to reflect API update

sorting.cpp

@@ -27,18 +27,18 @@ vector<int> merge(vector<int> first,vector<int> second){
         
         
         if (left == 1){
-             v.push_back(first[countFirst]);
+            v.push_back(first[countFirst]);
             if ( first.size()> countFirst){
                 countFirst+=1;
             }
-
+            
         }
         else{
-                v.push_back(second[countSecond]);
+            v.push_back(second[countSecond]);
             if (second.size()> countSecond){
                 countSecond+=1;
             }
-      
+            
         }
         
     }
@@ -57,8 +57,29 @@ vector<int> mergeSorting(vector<int> v){
 }
 
 
-vector<int> sort_custom(vector<int> v){
-    vector<int> sortVec = mergeSorting(v);
-    return sortVec;
+vector<int> sort_custom(vector<int> v , int startidx, int endidx){
+    
+    int size = v.size();
+    if (size < endidx   || startidx > endidx) {
+        
+        cout  << "Invalid Input ";
+        vector<int> v;
+        return v;
+    }
+    else {
+        vector<int> initVector(v.cbegin(), v.cbegin()+startidx);
+        vector<int> subVector(v.cbegin()+startidx, v.cbegin()+endidx+1);
+        vector<int>  endVector(v.cbegin()+endidx+1, v.cend());
+        
+        vector<int> sortVec = mergeSorting(subVector);
+        
+        initVector.insert( initVector.end(), sortVec.begin(), sortVec.end() );
+        initVector.insert( initVector.end(), endVector.begin(), endVector.end() );
+        
+        return initVector;
+    }
+    
+    
+    
 }