/**
 * 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 {
    bool Match(TreeNode* s, TreeNode* t) {
        if (s==nullptr&&t==nullptr)
            return true;
        if (s==nullptr||t==nullptr)
            return false;
        if (s->val!=t->val)
            return false;
        return Match(s->left, t->left)&&Match(s->right, t->right);
    }
    bool Traverse(TreeNode* s, TreeNode* t) {
        if (s==nullptr)
            return t==nullptr;
        if (s->val==t->val) {
            if (Match(s,t))
                return true;
        }
        return Traverse (s->left, t)||Traverse(s->right, t);

    }
public:
    bool isSubtree(TreeNode* s, TreeNode* t) {
        return Traverse(s,t);
    }
};