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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool isSubtree(TreeNode* s, TreeNode* t) {
        if(!s) return false;
        if(isSame(s,t)) return true;
        return isSubtree(s->left,t) || isSubtree(s->right,t);
    }
    bool isSame(TreeNode *s, TreeNode *t){
        if (!s && !t) return true;
        if (!s || !t) return false;
        if (s->val != t->val) return false;
        return isSame(s->left, t->left) && isSame(s->right, t->right);
    }
};

-------------------

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool isSubtree(TreeNode* root, TreeNode* subRoot) {
        string text = serialize(root);
        string pat = serialize(subRoot);
        return text.find(pat) != string::npos;
    }

    std::hash<std::string> str_hash;
    string serialize(TreeNode *root){
        if(!root) return "#";
        return to_string(str_hash(to_string(root->val)))+","+serialize(root->left)+","+serialize(root->right);
    }

};