添加（0222.完全二叉树的节点个数.md）：增加typescript版本

problems/0222.完全二叉树的节点个数.md

@@ -447,7 +447,63 @@ var countNodes = function(root) {
 };
 ```
 
+## TypeScrpt:
+
+> 递归法
+
+```typescript
+function countNodes(root: TreeNode | null): number {
+    if (root === null) return 0;
+    return 1 + countNodes(root.left) + countNodes(root.right);
+};
+```
+
+> 迭代法
+
+```typescript
+function countNodes(root: TreeNode | null): number {
+    let helperQueue: TreeNode[] = [];
+    let resCount: number = 0;
+    let tempNode: TreeNode;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            resCount++;
+            if (tempNode.left) helperQueue.push(tempNode.left);
+            if (tempNode.right) helperQueue.push(tempNode.right);
+        }
+    }
+    return resCount;
+};
+```
+
+> 利用完全二叉树性质
+
+```typescript
+function countNodes(root: TreeNode | null): number {
+    if (root === null) return 0;
+    let left: number = 0,
+        right: number = 0;
+    let curNode: TreeNode | null= root;
+    while (curNode !== null) {
+        left++;
+        curNode = curNode.left;
+    }
+    curNode = root;
+    while (curNode !== null) {
+        right++;
+        curNode = curNode.right;
+    }
+    if (left === right) {
+        return 2 ** left - 1;
+    }
+    return 1 + countNodes(root.left) + countNodes(root.right);
+};
+```
+
 ## C:
+
 递归法
 ```c
 int countNodes(struct TreeNode* root) {