add 1261

Author: cshanbo

1261.find_elements_in_a_contaminated_tree.cpp

@@ -0,0 +1,31 @@
+//coding:utf-8
+/***********************************************************
+Program: 1261
+Description: I think this one should be categorized as `easy`.
+Shanbo Cheng: [email protected]
+Date: 2020-01-09 21:31:49
+Last modified: 2020-01-09 21:32:26
+GCC version: 4.9.3
+***********************************************************/
+
+class FindElements {
+    unordered_set<int> vals;
+public:
+    void helper(TreeNode* root, int val) {
+        if(!root)
+            return;
+        root->val = val;
+        vals.insert(val);
+        if(root->left)
+            helper(root->left, 2 * root->val + 1);
+        if(root->right)
+            helper(root->right, 2 * root->val + 2);
+    }
+    FindElements(TreeNode* root) {
+        helper(root, root->val + 1);
+    }
+    
+    bool find(int target) {
+        return vals.find(target) != vals.end();
+    }
+};