添加（0129.求根到叶子节点数字之和.md）：增加typescript版本

Author: xiaofei-2020

problems/0129.求根到叶子节点数字之和.md

@@ -289,7 +289,40 @@ var sumNumbers = function(root) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function sumNumbers(root: TreeNode | null): number {
+    if (root === null) return 0;
+    let resTotal: number = 0;
+    const route: number[] = [];
+    route.push(root.val);
+    recur(root, route);
+    return resTotal;
+    function recur(node: TreeNode, route: number[]): void {
+        if (node.left === null && node.right === null) {
+            resTotal += listToSum(route);
+            return;
+        }
+        if (node.left !== null) {
+            route.push(node.left.val);
+            recur(node.left, route);
+            route.pop();
+        };
+        if (node.right !== null) {
+            route.push(node.right.val);
+            recur(node.right, route);
+            route.pop();
+        };
+    }
+    function listToSum(nums: number[]): number {
+        return Number(nums.join(''));
+    }
+};
+```
+
 C:
+
 ```c
 //sum记录总和
 int sum;