添加（0101.对称二叉树.md）：增加typescript版本

problems/0101.对称二叉树.md

@@ -574,6 +574,75 @@ var isSymmetric = function(root) {
 };
 ```
 
+## TypeScript：
+
+> 递归法
+
+```typescript
+function isSymmetric(root: TreeNode | null): boolean {
+    function recur(node1: TreeNode | null, node2: TreeNode | null): boolean {
+        if (node1 === null && node2 === null) return true;
+        if (node1 === null || node2 === null) return false;
+        if (node1.val !== node2.val) return false
+        let isSym1: boolean = recur(node1.left, node2.right);
+        let isSym2: boolean = recur(node1.right, node2.left);
+        return isSym1 && isSym2
+    }
+    if (root === null) return true;
+    return recur(root.left, root.right);
+};
+```
+
+> 迭代法
+
+```typescript
+// 迭代法(队列)
+function isSymmetric(root: TreeNode | null): boolean {
+    let helperQueue: (TreeNode | null)[] = [];
+    let tempNode1: TreeNode | null,
+        tempNode2: TreeNode | null;
+    if (root !== null) {
+        helperQueue.push(root.left);
+        helperQueue.push(root.right);
+    }
+    while (helperQueue.length > 0) {
+        tempNode1 = helperQueue.shift()!;
+        tempNode2 = helperQueue.shift()!;
+        if (tempNode1 === null && tempNode2 === null) continue;
+        if (tempNode1 === null || tempNode2 === null) return false;
+        if (tempNode1.val !== tempNode2.val) return false;
+        helperQueue.push(tempNode1.left);
+        helperQueue.push(tempNode2.right);
+        helperQueue.push(tempNode1.right);
+        helperQueue.push(tempNode2.left);
+    }
+    return true;
+}
+
+// 迭代法(栈)
+function isSymmetric(root: TreeNode | null): boolean {
+    let helperStack: (TreeNode | null)[] = [];
+    let tempNode1: TreeNode | null,
+        tempNode2: TreeNode | null;
+    if (root !== null) {
+        helperStack.push(root.left);
+        helperStack.push(root.right);
+    }
+    while (helperStack.length > 0) {
+        tempNode1 = helperStack.pop()!;
+        tempNode2 = helperStack.pop()!;
+        if (tempNode1 === null && tempNode2 === null) continue;
+        if (tempNode1 === null || tempNode2 === null) return false;
+        if (tempNode1.val !== tempNode2.val) return false;
+        helperStack.push(tempNode1.left);
+        helperStack.push(tempNode2.right);
+        helperStack.push(tempNode1.right);
+        helperStack.push(tempNode2.left);
+    }
+    return true;
+};
+```
+
 ## Swift:
 
 > 递归