572.txt

/**
 * 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 isSubtree(TreeNode* s, TreeNode* t) {
        if (s == nullptr) return false;
        if (isSame(s,t)) return true;
        else return isSubtree(s->left,t) || isSubtree(s->right,t);

        
    }
private:
    bool isSame(TreeNode* s, TreeNode* t){
        if(s == nullptr && t == nullptr) return true;
        else if(s == nullptr || t == nullptr) return false;
        if(s->val == t -> val){
            if (isSame(s->left,t->left) && isSame(s->right,t->right)) return true;
            else return false;
        }
        else return false;
    }
};