Update TypeScript codes.

codes/typescript/module/ListNode.ts

@@ -7,26 +7,28 @@
 /**
  * Definition for a singly-linked list node
  */
-export default class ListNode {
+class ListNode {
     val: number;
     next: ListNode | null;
     constructor(val?: number, next?: ListNode | null) {
         this.val = val === undefined ? 0 : val;
         this.next = next === undefined ? null : next;
     }
-
-    /**
-     * Generate a linked list with an array
-     * @param arr
-     * @return
-     */
-    arrToLinkedList(arr: number[]): ListNode | null {
-        const dum: ListNode = new ListNode(0);
-        let head = dum;
-        for (const val of arr) {
-            head.next = new ListNode(val);
-            head = head.next;
-        }
-        return dum.next;
-    }
 }
+
+/**
+ * Generate a linked list with an array
+ * @param arr
+ * @return
+ */
+function arrToLinkedList(arr: number[]): ListNode | null {
+    const dum: ListNode = new ListNode(0);
+    let head = dum;
+    for (const val of arr) {
+        head.next = new ListNode(val);
+        head = head.next;
+    }
+    return dum.next;
+}
+
+export { ListNode, arrToLinkedList };

codes/typescript/module/PrintUtil.ts

@@ -4,7 +4,7 @@
  * Author: Justin (xiefahit@gmail.com)
  */
 
-import ListNode from './ListNode';
+import { ListNode } from './ListNode';
 import { TreeNode } from './TreeNode';
 
 /**