binary search tree

Author: da183

advanced_algorithm/binary_search_tree.md

@@ -12,44 +12,47 @@
 > 验证二叉搜索树
 
 ```c++
-struct Result {
-    TreeNode *maxNode;
-    TreeNode *minNode;
-    bool isValidate;
+class Solution {
+public:
+    struct Result {
+        TreeNode *maxNode;
+        TreeNode *minNode;
+        bool isValidate;
 
-    Result(bool validate = true, TreeNode *max = nullptr, TreeNode *min = nullptr)
-            : isValidate(validate), maxNode(max), minNode(min) {
+        Result(bool validate = true, TreeNode *max = nullptr, TreeNode *min = nullptr)
+                : isValidate(validate), maxNode(max), minNode(min) {
 
+        }
+    };
+    bool isValidBST(TreeNode *root) {
+        if (!root) {
+            return true;
+        }
+        return helper(root).isValidate;
+    }
+
+    Result helper(TreeNode *root) {
+        if (!root) {
+            return {};
+        }
+        auto left = helper(root->left);
+        auto right = helper(root->right);
+        if (!(left.isValidate && right.isValidate)) {
+            return {false};
+        }
+        if (left.maxNode && left.maxNode->val >= root->val) {
+            return {false};
+        }
+        if (right.minNode && right.minNode->val <= root->val) {
+            return {false};
+        }
+        return {
+                true,
+                right.maxNode ? right.maxNode : root,
+                left.minNode ? left.minNode : root,
+        };
     }
 };
-bool isValidBST(TreeNode *root) {
-    if (!root) {
-        return true;
-    }
-    return helper(root).isValidate;
-}
-
-Result helper(TreeNode *root) {
-    if (!root) {
-        return {};
-    }
-    auto left = helper(root->left);
-    auto right = helper(root->right);
-    if (!(left.isValidate && right.isValidate)) {
-        return {false};
-    }
-    if (left.maxNode && left.maxNode->val >= root->val) {
-        return {false};
-    }
-    if (right.minNode && right.minNode->val <= root->val) {
-        return {false};
-    }
-    return {
-            true,
-            right.maxNode ? right.maxNode : root,
-            left.minNode ? left.minNode : root,
-    };
-}
 ```
 
 [insert-into-a-binary-search-tree](https://leetcode-cn.com/problems/insert-into-a-binary-search-tree/)