Solution as on 29-07-2022 10:00 pm

Author: knockcat

0114. Flatten Binary Tree to Linked List.cpp

@@ -0,0 +1,46 @@
+// 114.✅ Flatten Binary Tree to Linked List
+
+class Solution
+{
+public:
+    void flatten(TreeNode *root)
+    {
+
+        if (root == nullptr)
+            return;
+
+        stack<TreeNode *> st;
+        st.push(root);
+
+        while (!st.empty())
+        {
+            TreeNode *curr = st.top();
+            st.pop();
+            if (curr->right)
+                st.push(curr->right);
+            if (curr->left)
+                st.push(curr->left);
+            if (!st.empty())
+                curr->right = st.top();
+            curr->left = nullptr;
+        }
+    }
+};
+
+// Another Approach
+
+class Solution
+{
+public:
+    TreeNode *prev = nullptr;
+    void flatten(TreeNode *root)
+    {
+        if (root == nullptr)
+            return;
+        flatten(root->right);
+        flatten(root->left);
+        root->right = prev;
+        root->left = nullptr;
+        prev = root;
+    }
+};