LeetCode 114 Flatten Binary Tree to Linked List

题目描述

Given a binary tree, flatten it to a linked list in-place.

For example,
Given

The flattened tree should look like:

代码

    TreeNode prev;    void preorder(TreeNode root) {        if (root == null)            return;        TreeNode left = root.left;        TreeNode right = root.right;        // root        if (prev != null) {            prev.right = root;            prev.left = null;        }        prev = root;        preorder(left);        preorder(right);    }    public void flatten(TreeNode root) {        prev = null;        preorder(root);    }