feat: solve new question

Author: arwildo

merge-two-sorted-lists/main.js

@@ -0,0 +1,34 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} list1
+ * @param {ListNode} list2
+ * @return {ListNode}
+ */
+var mergeTwoLists = function(list1, list2) {
+    let dummy = new ListNode();
+    let tail = dummy;
+
+    while (list1 !== null && list2 !== null) {
+        if (list1.val < list2.val) {
+            tail.next = list1;
+            list1 = list1.next
+        } else {
+            tail.next = list2;
+            list2 = list2.next;
+        }
+        tail = tail.next;
+    }
+    if (list1 !== null) {
+        tail.next = list1;
+    } else if (list2 !== null) {
+        tail.next = list2;
+    }
+    return dummy.next;
+};
+