题目:

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

    }

    public boolean HasSubtree(TreeNode root1, TreeNode root2) {
          if (root1 == null || root2 == null) {
            return false;
        }
        boolean flag = false;
        if (root1.val == root2.val) {
            flag =  HasSimTree(root1, root2);
        }
        return  flag || HasSubtree(root1.left, root2) || HasSubtree(root1.right, root2);
    }
}

判断当前节点包不包含b结构需要递归 再写个方法即可。