剑指offer编程题—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）

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
public:
    bool HasSubtree(TreeNode* pRoot1, TreeNode* pRoot2)
    {
        if(pRoot1==NULL || pRoot2==NULL)
            return false;
        return IsSubtree(pRoot1,pRoot2) || HasSubtree(pRoot1->left,pRoot2) || HasSubtree(pRoot1->right,pRoot2);
    }
    bool IsSubtree(TreeNode* pRoot1, TreeNode* pRoot2)
    {
        if(pRoot2==NULL)
            return true;
        if(pRoot1==NULL)
            return false;
        if(pRoot1->val!=pRoot2->val)
            return false;
        return IsSubtree(pRoot1->left,pRoot2->left) && IsSubtree(pRoot1->right,pRoot2->right);
    }
};