题目链接

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题目描述

输入两棵二叉树A，B，判断B是不是A的子结构。（ps：我们约定空树不是任意一个树的子结构）

解题思路

public class Solution {
   
    public boolean HasSubtree(TreeNode root1,TreeNode root2) {
   
        if (root1==null || root2==null) return false;
        return isSubTreeWithRoot(root1, root2) || HasSubtree(root1.left, root2) || HasSubtree(root1.right, root2);
    }
    private boolean isSubTreeWithRoot(TreeNode node1, TreeNode node2) {
   
        if (node2==null) return true;
        if (node1==null) return false;
        if (node1.val != node2.val) return false;
        return isSubTreeWithRoot(node1.left, node2.left) && isSubTreeWithRoot(node1.right, node2.right);
    }
}