剑指offer 面试题62 序列化和反序列化二叉树

剑指offer 面试题62 序列化和反序列化二叉树

题目：
请实现两个函数，分别用来序列化和反序列化二叉树。

package algorithm.ac.foroffer.top70;import org.junit.Test;import java.util.LinkedList;/** * description: * * @author liyazhou * @create 2017-06-19 11:08 * * 面试题62：序列化二叉树 * * 题目： *      请实现两个函数，分别用来序列化和反序列化二叉树。 *                    1 *                  /  \ *                2     3 *               /     / \ *              4     5  6 * * 考查点： *      1. 二叉树 * * 思路： *      1. 序列化二叉树，采用前序遍历的方式 *            而且要保证任何结点均有两个孩子，若没有孩子或者只有一个孩子，则将缺失的孩子设置为 null *      2. 反序列化二叉树， * */class BinTreeNode62{    int value;    BinTreeNode62 left;    BinTreeNode62 right;    public BinTreeNode62(){}    public BinTreeNode62 (int _value){ value = _value; }    public void setChildren(BinTreeNode62 _left, BinTreeNode62 _right){        left = _left;        right = _right;    }}public class Test62 {    /**     * 序列化二叉树     * @param root 二叉树的根结点     * @return 序列化后的字符串     */    public String serializeToString(BinTreeNode62 root){        if (root == null) return null;        String[] sequence = new String[]{""};        serializeToString(root, sequence);        return sequence[0].substring(1);    }    private void serializeToString(BinTreeNode62 root, String[] sequence){        if (root == null) {            sequence[0] += ",#";            return;        }        else sequence[0] += ("," + root.value);        serializeToString(root.left, sequence);        serializeToString(root.right, sequence);    }    /**     * 反序列化二叉树     * @param sequence 序列化后的二叉树     * @return 二叉树的根结点     */    public BinTreeNode62 deserializeToBinTree(String sequence){        if (sequence == null || sequence.length() == 0) return null;        String[] values = sequence.split(",");        return deserializeToBinTree(values, new int[]{0});    }    private BinTreeNode62 deserializeToBinTree(String[] values, int[] index) {        String value = values[index[0]++];        BinTreeNode62 root = null;        if (value.matches("[0-9]+")){            root = new BinTreeNode62();            root.value = Integer.valueOf(value);            // System.out.println(root.value);            root.left = deserializeToBinTree(values, index);            root.right = deserializeToBinTree(values, index);        }        return root;    }    @Test    public void test(){        BinTreeNode62 node1 = new BinTreeNode62(1);        BinTreeNode62 node2 = new BinTreeNode62(2);        BinTreeNode62 node3 = new BinTreeNode62(3);        BinTreeNode62 node4 = new BinTreeNode62(4);        BinTreeNode62 node5 = new BinTreeNode62(5);        BinTreeNode62 node6 = new BinTreeNode62(6);        node1.setChildren(node2, node3);        node2.setChildren(node4, null);        node3.setChildren(node5, node6);        String sequence = serializeToString(node1);        System.out.println(sequence);  // 1,2,4,#,#,#,3,5,#,#,6,#,#        BinTreeNode62 root = deserializeToBinTree(sequence);        System.out.println("-------------------");        System.out.println(root.value);        System.out.println(root.left.value);        System.out.println(root.left.left.value);        System.out.println(root.right.value);        System.out.println(root.right.left.value);        System.out.println(root.right.right.value);        LinkedList<BinTreeNode62> queue = new LinkedList<>();        queue.offer(root);        while (!queue.isEmpty()){            BinTreeNode62 node = queue.poll();            System.out.print(node.value + "\t");            if (node.left != null) queue.offer(node.left);            if (node.right != null) queue.offer(node.right);        }    }}