Create 1110. Delete Nodes And Return Forest (#532)

Author: Chayandas07

1110. Delete Nodes And Return Forest

@@ -0,0 +1,41 @@
+/**
+ * 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 Solution {
+
+private:
+    void unlinker(TreeNode* &root, unordered_map<int,bool> &del, vector<TreeNode*> &ans){
+        if(!root) return;
+
+        unlinker(root->left,del,ans);
+        unlinker(root->right,del,ans);
+
+        if(del[root->val]){
+            if(root->left) ans.push_back(root->left);
+            if(root->right) ans.push_back(root->right);
+            root = NULL;
+        }
+    }
+
+public:
+    vector<TreeNode*> delNodes(TreeNode* root, vector<int>& to_delete) {
+        
+        unordered_map<int,bool> del;
+        for(int i : to_delete) del[i] = true;
+
+        vector<TreeNode*> ans;
+        unlinker(root,del,ans);
+        if(root) ans.push_back(root);
+
+        return ans;
+    }
+};