Update mergeList.cpp

Lecture049 Linked List Day6/mergeList.cpp

@@ -1,3 +1,5 @@
+#include <bits/stdc++.h>
+
 /************************************************************
 
     Following is the linked list node structure.
@@ -22,50 +24,73 @@
 
 ************************************************************/
 
-void solve(Node<int>* first, Node<int>* second) {
+Node<int>* solve(Node<int>* first, Node<int>* second) {
+
+      //check first LL have only one node
+
+    if(first -> next == NULL){
+
+        first -> next = second;
+
+        return first;
+
+    }
 
 
-    Node* curr1 = first;
-    Node* next1 = curr1 -> next;
+    Node<int>* curr1 = first;
+    Node<int>* next1 = curr1 -> next;
 
-    Node* curr2 = second;
-    Node* next2 = curr2 -> next;
+    Node<int>* curr2 = second;
+    Node<int>* next2 = curr2 -> next;
 
     while(next1 != NULL && curr2 != NULL) {
 
         if( (curr2 -> data >= curr1 -> data ) 
            && ( curr2 -> data <= next1 -> data)) {
 
-            curr1 -> next = curr2;
+          curr1 -> next = curr2;
+            next2 = curr2->next; // Update next2 before moving curr2
             curr2 -> next = next1;
+
+            // Move curr1 to curr2, which is now the last merged node
             curr1 = curr2;
             curr2 = next2;
         }
-        else {
-
-        }
+         else{
+             // move curr1 and next1
+
+             curr1=next1;
+             next1=next1->next;
+
+             if(next1==NULL){
+                 curr1->next=curr2;
+                 return first;
+             }
+         }
 
 
     }
+    return first;
 
 
 }
 
+
 Node<int>* sortTwoLists(Node<int>* first, Node<int>* second)
 {
+    // Write your code here.
     if(first == NULL)
         return second;
 
     if(second == NULL)
         return first;
 
     if(first -> data <= second -> data ){
-        solve(first, second);
+        return solve(first, second);
     }
     else
     {
-        solve(second, first);
+        return solve(second, first);
     }
 
-
 }