剑指Offer-二叉树的镜像

package Tree;

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;

/**
 * 二叉树的镜像
 * 操作给定的二叉树，将其变换为源二叉树的镜像。
 * 二叉树的镜像定义：源二叉树
 * 8
 * /  \
 * 6   10
 * / \  / \
 * 5  7 9 11
 * 镜像二叉树
 * 8
 * /  \
 * 10   6
 * / \  / \
 * 11 9 7  5
 * 思路：
 * 先前序遍历这棵树的每个结点，如果遍历到的结点有子结点，就交换它的两个子节点，
 * 当交换完所有的非叶子结点的左右子结点之后，就得到了树的镜像
 */
public class Solution15 {
    public static void main(String[] args) {
        Solution15 solution15 = new Solution15();
        int[] array = {8, 6, 10, 5, 7, 9, 11};
        TreeNode treeNode = solution15.createBinaryTreeByArray(array, 0);
        System.out.println(treeNode.left.right.val);
        solution15.Mirror_2(treeNode);
        System.out.println(treeNode.left.right.val);

    }

    /**
     * 用栈遍历二叉树
     *
     * @param root
     */
    public void Mirror_2(TreeNode root) {
        if (root == null) {
            return;
        }
        Deque<TreeNode> deque = new ArrayDeque<>();
        deque.push(root);
        while (!deque.isEmpty()) {
            TreeNode node = deque.pop();
            if (node.left != null || node.right != null) {
                TreeNode temp = node.left;
                node.left = node.right;
                node.right = temp;
            }
            if (node.left != null) {
                deque.push(node.left);
            }
            if (node.right != null) {
                deque.push(node.right);
            }
        }


    }

    /**
     * 递归
     *
     * @param root
     */
    public void Mirror(TreeNode root) {
        if (root == null) {
            return;
        }
        if (root.left == null && root.right == null) {
            return;
        }
        TreeNode temp = root.left;
        root.left = root.right;
        root.right = temp;
        if (root.left != null) {
            Mirror(root.left);
        }
        if (root.right != null) {
            Mirror(root.right);
        }
    }

    public class TreeNode {
        int val = 0;
        TreeNode left = null;
        TreeNode right = null;

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

        }

    }

    public TreeNode createBinaryTreeByArray(int[] array, int index) {
        TreeNode tn = null;
        if (index < array.length) {
            int value = array[index];
            tn = new TreeNode(value);
            tn.left = createBinaryTreeByArray(array, 2 * index + 1);
            tn.right = createBinaryTreeByArray(array, 2 * index + 2);
            return tn;
        }
        return tn;
    }
}