Merge branch 'youngyangyang04:master' into master

Author: SianXiaoCHN

problems/0134.加油站.md

@@ -78,7 +78,7 @@ public:
 ```
 
 * 时间复杂度：$O(n^2)$
-* 空间复杂度：$O(n)$
+* 空间复杂度：$O(1)$
 
 C++暴力解法在leetcode上提交也可以过。
 

problems/0538.把二叉搜索树转换为累加树.md

@@ -312,5 +312,47 @@ struct TreeNode* convertBST(struct TreeNode* root){
 }
 ```
 
+## TypeScript
+
+> 递归法
+
+```typescript
+function convertBST(root: TreeNode | null): TreeNode | null {
+    let pre: number = 0;
+    function recur(root: TreeNode | null): void {
+        if (root === null) return;
+        recur(root.right);
+        root.val += pre;
+        pre = root.val;
+        recur(root.left);
+    }
+    recur(root);
+    return root;
+};
+```
+
+> 迭代法
+
+```typescript
+function convertBST(root: TreeNode | null): TreeNode | null {
+    const helperStack: TreeNode[] = [];
+    let curNode: TreeNode | null = root;
+    let pre: number = 0;
+    while (curNode !== null || helperStack.length > 0) {
+        while (curNode !== null) {
+            helperStack.push(curNode);
+            curNode = curNode.right;
+        }
+        curNode = helperStack.pop()!;
+        curNode.val += pre;
+        pre = curNode.val;
+        curNode = curNode.left;
+    }
+    return root;
+};
+```
+
+
+
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