MirrorTree.java

package SwordToOffer;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;

/**
 * Created by tlh on 2017/3/13.
 */
public class MirrorTree {
    public class TreeNode {
        int val = 0;
        TreeNode left = null;
        TreeNode right = null;

        public TreeNode(int val) {
            this.val = val;
        }
    }

    public void Mirror(TreeNode root) {
        doMirror(root);
    }

    private TreeNode doMirror(TreeNode root) {
        if (root == null) return null;
        TreeNode left = root.left;
        TreeNode right = root.right;

        root.left = doMirror(right);
        root.right = doMirror(left);
        return root;
    }

    public ArrayList<Integer> PrintFromTopToBottom(TreeNode root) {
        ArrayList<Integer> result = new ArrayList<>();
        Queue<TreeNode> queue = new LinkedList<>();
        if (root == null)
            return result;
        queue.offer(root);
        while (!queue.isEmpty()) {
            TreeNode node = queue.poll();
            if (node == null)
                continue;
            result.add(node.val);
            queue.add(node.left);
            queue.add(node.right);
        }
        return result;
    }
}