C++ 代码

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
     bool hasSubtree(TreeNode* pRoot1, TreeNode* pRoot2) {

        string s1 = "";
        string s2 = "";
        dfs(pRoot1,s1);
        dfs(pRoot2,s2);
        if(s1.size() == 0 && s2.size() == 0)
        return true;
        if(s1.size() == 0 || s2.size() == 0)
        return false;
        return !(s1.find(s2) == s1.npos);
    }
    void dfs(TreeNode *p,string &str)
    {

        if(!p)
        return;
        str += to_string(p->val);
        dfs(p -> left,str);
        dfs(p -> right,str);
    }
};