Create MergeTwoSortedLists.java

Author: techieJarek

MergeTwoSortedLists.java

@@ -0,0 +1,72 @@
+/**
+ Merge two sorted linked lists and return it as a new list. The new list should be made by
+ splicing together the nodes of the first two lists.
+ */
+public class MergeTwoSortedLists {
+    public static void main(String[] args){
+        ListNode n1 = new ListNode(1);
+        ListNode n11 = new ListNode(2);
+        ListNode n111 = new ListNode(4);
+        n1.next = n11;
+        n11.next = n111;
+        ListNode n2 = new ListNode(1);
+        ListNode n22 = new ListNode(3);
+        ListNode n222 = new ListNode(4);
+        n2.next = n22;
+        n22.next = n222;
+
+        ListNode node = mergeTwoLists(n1, n2);
+        printListValues(node);
+    }
+
+    private static void printListValues(ListNode node) {
+        while(node!=null){
+            System.out.print(node.val);
+            if(node.next!=null){
+                System.out.print("->");
+            }
+            node = node.next;
+        }
+    }
+
+    public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {
+        if(l1==null && l2!=null) return l2;
+        if(l2==null && l1!=null) return l1;
+        if(l2==null && l1==null) return null;
+        ListNode node = (l1.val < l2.val) ? l1 : l2;
+        if(l1.val < l2.val){
+            l1 = l1.next;
+        }
+        else{
+            l2 = l2.next;
+        }
+
+        ListNode parent = node;
+        while (l1!=null || l2!=null){
+            if(l1!=null && l2==null){
+                parent.next = new ListNode(l1.val);
+                l1 = l1.next;
+            }
+            else if(l2!=null && l1==null){
+                parent.next = new ListNode(l2.val);
+                l2 = l2.next;
+            }
+            else{
+                parent.next = new ListNode(Integer.min(l1.val, l2.val));
+                if(l1.val < l2.val) {
+                    l1 = l1.next;
+                } else {
+                    l2 = l2.next;
+                }
+            }
+            parent = parent.next;
+        }
+
+        return node;
+    }
+    public static class ListNode {
+        int val;
+        ListNode next;
+        ListNode(int x) { val = x; }
+    }
+}