173

LeetCode/173v2.cc

@@ -0,0 +1,42 @@
+/**
+ * Definition for a binary tree node.
+ * 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 BSTIterator {
+    vector<int> q;
+    int it{0};
+
+    void helper(TreeNode* cur) {
+        if(!cur) return;
+        helper(cur->left);
+        q.emplace_back(cur->val);
+        helper(cur->right);
+    }
+
+public:
+    BSTIterator(TreeNode* root) {
+        helper(root);
+    }
+
+    int next() {
+        return q[it++];
+    }
+
+    bool hasNext() {
+        return it < q.size();
+    }
+};
+
+/**
+ * Your BSTIterator object will be instantiated and called as such:
+ * BSTIterator* obj = new BSTIterator(root);
+ * int param_1 = obj->next();
+ * bool param_2 = obj->hasNext();
+ */