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）

 

/**
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) {
        if(null == root2 || null == root1){
            return false;
        }
        
        return sub(root1, root2, root2);
    }
    
    public boolean sub(TreeNode root1, TreeNode root2, TreeNode tmp){
        if(null == root2){
            return true;
        }
        if(null == root1){
            return false;
        }
        
        if(root1.val == root2.val 
           && sub(root1.left, root2.left, tmp) && sub(root1.right, root2.right, tmp)){
            return true;
        }
        return sub(root1.left, tmp, tmp) || sub(root1.right, tmp, tmp);
    }
}