Create change-the-root-of-a-binary-tree.cpp

Author: kamyu104

C++/change-the-root-of-a-binary-tree.cpp

@@ -0,0 +1,38 @@
+// Time:  O(h)
+// Space: O(1)
+
+/*
+// Definition for a Node.
+class Node {
+public:
+    int val;
+    Node* left;
+    Node* right;
+    Node* parent;
+};
+*/
+
+class Solution {
+public:
+    Node* flipBinaryTree(Node* root, Node * leaf) {
+        Node *curr = leaf, *parent = nullptr;
+        while (true) {
+            auto child = curr->parent;
+            curr->parent = parent;
+            if (curr->left == parent) {
+                curr->left = nullptr;
+            } else {
+                curr->right = nullptr;
+            }
+            if (curr == root) {
+                break;
+            }
+            if (curr->left) {
+                curr->right = curr->left;
+            }
+            curr->left = child;
+            parent = curr, curr = child;
+        }
+        return leaf;
+    }
+};