添加（429.N叉树的层序遍历）：增加typescript版本

problems/0102.二叉树的层序遍历.md

@@ -1190,7 +1190,30 @@ var levelOrder = function(root) {
 };
 ```
 
+TypeScript:
+
+```typescript
+function levelOrder(root: Node | null): number[][] {
+    let helperQueue: Node[] = [];
+    let resArr: number[][] = [];
+    let tempArr: number[] = [];
+    if (root !== null) helperQueue.push(root);
+    let curNode: Node;
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            curNode = helperQueue.shift()!;
+            tempArr.push(curNode.val);
+            helperQueue.push(...curNode.children);
+        }
+        resArr.push(tempArr);
+        tempArr = [];
+    }
+    return resArr;
+};
+```
+
 Swift:
+
 ```swift
 func levelOrder(_ root: Node?) -> [[Int]] {
     var res = [[Int]]()