【0807】相同的树

class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(p == nullptr && q == nullptr){
            return true;
        } else if(p == nullptr || q == nullptr){
            return false;
        } else if(p->val != q->val){
            return false;
        } else {
            return isSameTree(p->left, q->left) && isSameTree(p->right, q->right); 
        }
    }
};