add solution: merge-two-sorted-lists

Author: yihyun-kim1

merge-two-sorted-lists/yihyun-kim1.js

@@ -0,0 +1,31 @@
+/**
+ * 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}
+ */
+const mergeTwoLists = (list1, list2) => {
+  const dummy = new ListNode(0);
+  let current = dummy;
+
+  while (list1 !== null && list2 !== null) {
+    if (list1.val <= list2.val) {
+      current.next = list1;
+      list1 = list1.next;
+    } else {
+      current.next = list2;
+      list2 = list2.next;
+    }
+    current = current.next;
+  }
+
+  current.next = list1 || list2;
+
+  return dummy.next;
+};