Create find-elements-in-a-contaminated-binary-tree.cpp

Author: kamyu104

C++/find-elements-in-a-contaminated-binary-tree.cpp

@@ -0,0 +1,35 @@
+// Time:  O(n)
+// Space: O(h)
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class FindElements {
+public:
+    FindElements(TreeNode* root) {
+        dfs(root, 0, &lookup_);
+    }
+    
+    bool find(int target) {
+        return lookup_.count(target);
+    }
+
+private:
+    void dfs(TreeNode *node, int v, unordered_set<int> *lookup) {
+        if (!node) {
+            return;
+        }
+        node->val = v;
+        lookup->emplace(v);
+        dfs(node->left, 2 * v + 1, lookup);
+        dfs(node->right, 2 * v + 2, lookup);
+    }
+
+    unordered_set<int> lookup_;
+};