Initial commit

Medium/validate-binary-search-tree/solution.cpp

@@ -0,0 +1,29 @@
+struct TreeNode {
+    int val;
+    TreeNode *left;
+    TreeNode *right;
+    TreeNode() : val(0), left(nullptr), right(nullptr) {}
+    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+    TreeNode(int x, TreeNode *left, TreeNode *right)
+        : val(x), left(left), right(right) {}
+};
+
+class Solution {
+  private:
+    bool isValidBST(TreeNode *root, int *minptr, int *maxptr) {
+        if (root == nullptr) {
+            return true;
+        } else if ((maxptr != nullptr && *maxptr <= root->val) ||
+                   (minptr != nullptr && *minptr >= root->val)) {
+            return false;
+        } else {
+            return isValidBST(root->left, minptr, &root->val) &&
+                   isValidBST(root->right, &root->val, maxptr);
+        }
+    }
+
+  public:
+    bool isValidBST(TreeNode *root) {
+        return isValidBST(root, nullptr, nullptr);
+    }
+};