剑指offer 树的子结构

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题目描述

输入两颗二叉树A，B，判断B是不是A的子结构。

/**public class TreeNode {    int val = 0;    TreeNode left = null;    TreeNode right = null;    public TreeNode(int val) {        this.val = val;    }}*/public class Solution {    public boolean HasSubtree(TreeNode root1, TreeNode root2) {        boolean result = false;        if (root1 != null && root2 != null) {            if (root1.val == root2.val) {                result = DoesTree1HaveTree2(root1, root2);            }            if (!result) {                result = HasSubtree(root1.left, root2);            }            if (!result) {                result = HasSubtree(root1.right, root2);            }        }        return result;    }    public boolean DoesTree1HaveTree2(TreeNode root1, TreeNode root2) {        if (root2 == null) {            return true;        }        if (root1 == null) {            return false;        }        if (root1.val != root2.val) {            return false;        }        return DoesTree1HaveTree2(root1.left, root2.left) &&                DoesTree1HaveTree2(root1.right, root2.right);    }}

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