经典考题。水平翻转二叉树。
这个题有个额外的小故事：
Trivia:This problem was inspired by this original tweet by Max Howell:
Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.
Invert a binary tree.
4
/ \
2 7
/ \ / \
1 3 6 9
to
4
/ \
7 2
/ \ / \
9 6 3 1
DFS遍历。每一个root下的左右对换。
class Solution {
public TreeNode invertTree(TreeNode root) {
if(root == null) return null;
TreeNode newNode = root.left;
root.left = root.right;
root.right = newNode;
invertTree(root.left);
invertTree(root.right);
return root;
}
}
