添加（104.二叉树的最大深度）：增加typescript版本

problems/0102.二叉树的层序遍历.md

@@ -2131,7 +2131,28 @@ var maxDepth = function(root) {
 };
 ```
 
+TypeScript:
+
+```typescript
+function maxDepth(root: TreeNode | null): number {
+    let helperQueue: TreeNode[] = [];
+    let resDepth: number = 0;
+    let tempNode: TreeNode;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        resDepth++;
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            if (tempNode.left) helperQueue.push(tempNode.left);
+            if (tempNode.right) helperQueue.push(tempNode.right);
+        }
+    }
+    return resDepth;
+};
+```
+
 Swift:
+
 ```swift
 func maxDepth(_ root: TreeNode?) -> Int {
     guard let root = root else {