update DFS

Author: Danieldu

DFS/1261.find-elements-in-a-contaminated-binary-tree.cpp

@@ -0,0 +1,84 @@
+/*
+ * @lc app=leetcode id=1261 lang=cpp
+ *
+ * [1261] Find Elements in a Contaminated Binary Tree
+ */
+
+// @lc code=start
+/**
+ * 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) {}
+ * };
+ */
+
+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) {}
+ };
+
+/**
+ * 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) {}
+ * };
+ */
+#include "bits/stdc++.h"
+using namespace std;
+
+class FindElements {
+public:
+    FindElements(TreeNode* root) {
+
+        if (!root) return;
+
+        queue<TreeNode*> q;
+        root->val = 0;
+        q.emplace(root);
+        visited.emplace(0); 
+
+        while(!q.empty()){
+            TreeNode* current = q.front();
+            q.pop();
+
+            if(current->left){
+                current->left->val = 2*current->val+1;
+                q.push(current->left);
+                visited.emplace(current->left->val);
+            }
+            if(current->right){
+                current->right->val = 2*current->val+2;
+                q.push(current->right);
+                visited.emplace(current->right->val);
+            }
+        }
+    }
+    
+    bool find(int target) {
+        return visited.count(target);
+    }
+    private:
+    unordered_set<int> visited;
+};
+
+/**
+ * Your FindElements object will be instantiated and called as such:
+ * FindElements* obj = new FindElements(root);
+ * bool param_1 = obj->find(target);
+ */
+// @lc code=end
+