Merge k Sorted Lists

mergeKLists.java

@@ -0,0 +1,43 @@
+/**
+ * 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 mergeKLists(ListNode[] lists) {
+
+        //ListNode a = new ListNode();
+        if(lists.length==0){
+            return null;
+        }
+
+        for(int k=1; k<lists.length; k++) {
+            lists[k]=mergeTwoLists(lists[k],lists[k-1]);
+
+
+        }
+        return lists[lists.length-1];
+    }
+
+    public static ListNode mergeTwoLists(ListNode list1, ListNode list2) {
+        if(list1 == null){
+       return list2;
+       }
+        if(list2==null){
+            return list1;
+        }
+        if(list1.val<list2.val){
+            list1.next = mergeTwoLists(list1.next , list2);
+            return list1;
+        }
+        else{
+            list2.next = mergeTwoLists(list2.next , list1);
+        }
+         return list2;
+    }
+}