update 173

Author: geemaple

README.md

@@ -42,10 +42,10 @@ python problem.py https://www.lintcode.com/problem/92 -l cpp
 | [--] | [grind75.md](./list/grind75.md) | 64/75 | - |
 | [--] | [leetcode-lee215.md](./list/leetcode-lee215.md) | 2/34 | - |
 | [--] | [neetcode150.md](./list/neetcode150.md) | 118/150 | - |
+| [✅] | [9c-advanced.md](./list/9c-advanced.md) | 74/91 | 17 vips |
 | [✅] | [9c-dp.md](./list/9c-dp.md) | 42/45 | 3 vips |
 | [✅] | [geekbang.md](./list/geekbang.md) | 55/55 | - |
 | [✅] | [leetcode101.md](./list/leetcode101.md) | 183/184 | 1 vip |
-| [🔲] | [9c-advanced.md](./list/9c-advanced.md) | 73/91 | 17 vips |
 | [🔲] | [leetcode-contest.md](./list/leetcode-contest.md) | 10/40 | - |
 | [🔲] | [leetcode-google.md](./list/leetcode-google.md) | 0/7 | - |
 

leetcode/173.binary-search-tree-iterator.cpp

@@ -60,29 +60,28 @@
  * };
  */
 class BSTIterator {
-private:
-    TreeNode* node;
-    stack<TreeNode*> st;
 public:
+    TreeNode *cur;
+    stack<TreeNode *> st;
     BSTIterator(TreeNode* root) {
-        node = root;
+        cur = root;
     }
 
     int next() {
-        while (node) {
-            st.push(node);
-            node = node->left;
+        while (cur) {
+            st.push(cur);
+            cur = cur->left;
         }
 
-        node = st.top();
+        cur = st.top();
         st.pop();
-        int res = node->val;
-        node = node->right;
+        int res = cur->val;
+        cur = cur->right;
         return res;
     }
 
     bool hasNext() {
-        return (st.size() > 0 || node);
+        return (cur || !st.empty());
     }
 };
 

leetcode/173.binary-search-tree-iterator.py

@@ -57,23 +57,21 @@
 class BSTIterator:
 
     def __init__(self, root: Optional[TreeNode]):
-        self.node = root
+        self.cur = root
         self.stack = []
 
     def next(self) -> int:
-        while(self.node):
-            self.stack.append(self.node)
-            self.node = self.node.left
-
-        self.node = self.stack.pop()
-        res = self.node.val
-        self.node = self.node.right
+        while (self.cur):
+            self.stack.append(self.cur)
+            self.cur = self.cur.left
 
+        self.cur = self.stack.pop()
+        res = self.cur.val
+        self.cur = self.cur.right
         return res
 
     def hasNext(self) -> bool:
-        return len(self.stack) > 0 or self.node is not None
-
+        return (self.cur is not None or len(self.stack) > 0)
 
 # Your BSTIterator object will be instantiated and called as such:
 # obj = BSTIterator(root)

list/9c-advanced.md

@@ -107,5 +107,4 @@
 88. https://www.lintcode.com/problem/flatten-list/
 89. https://leetcode.com/problems/flatten-nested-list-iterator/
 90. https://www.lintcode.com/problem/flatten-2d-vector/
-
-- https://leetcode.com/problems/binary-search-tree-iterator/
+91. https://leetcode.com/problems/binary-search-tree-iterator/