Create 1666-change-the-root-of-a-binary-tree.js

Author: everthis

1666-change-the-root-of-a-binary-tree.js

@@ -0,0 +1,33 @@
+/**
+ * // Definition for a Node.
+ * function Node(val) {
+ *    this.val = val;
+ *    this.left = null;
+ *    this.right = null;
+ *    this.parent = null;
+ * };
+ */
+
+/**
+ * @param {Node} node
+ * @return {Node}
+ */
+const flipBinaryTree = function(root, leaf) {
+  function flip(node, from_node){
+    // set and break pointers between node and from_node
+    const p = node.parent
+    node.parent = from_node
+    if (node.left === from_node) node.left = null
+    if (node.right === from_node) node.right = null
+
+    // stopping condition
+    if (node === root) return node
+
+    // set right child
+    if (node.left) node.right = node.left
+    // set left child
+    node.left = flip(p, node)
+    return node
+  }
+  return flip(leaf, null)
+};