Create MergeTwoSortedLL.java

Author: Trmpsanjay

MergeTwoSortedLL.java

@@ -0,0 +1,61 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
+        // handling edge edge cases
+        // if only list 2 exists return list 2
+        if(l1==null)
+            return l2;
+        // if only list 1 exists return list 1
+        if(l2==null)
+            return l1;
+        // if no list exists return null
+        if(l1==null && l2 == null)
+            return null;
+        // creating two pointers to keep track new sorted linked list
+        ListNode head = null;
+        ListNode tail = null;
+        
+        while(l1 != null && l2 != null){
+            if(l1.val<l2.val){
+                if(head == null)
+                    head = tail = l1;
+                else{
+                    tail.next = l1;
+                    tail = l1;
+                }
+                l1= l1.next;
+            }
+            else{
+                if(head == null)
+                    head = tail = l2;
+                else{
+                    tail.next = l2;
+                    tail = l2;
+                }
+                l2 = l2.next;
+            }
+        }
+        
+        // now checking adding the remaining l1 or l2 list;
+        // making tail .next = null
+        if(tail!=null)
+        tail.next = null;
+        if(l1!=null)
+            tail.next = l1;
+        if(l2 != null)
+            tail.next = l2;
+        return head;
+        
+        
+        
+    }
+}