17树的子结构

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）

Java实现

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;

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

}

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 root1, TreeNode root2) {
        if (root2 == null)
            return true;
        if (root1 == null)
            return false;
        if (root1.val != root2.val)
            return false;
        return isSubTreeWithRoot(root1.left, root2.left) && isSubTreeWithRoot(root1.right, root2.right);
    }
}