leetcode[100] Same Tree

class Solution {
public:
    bool isSameTree(TreeNode *p, TreeNode *q) 
    {
        if (!p) return !q;
        if (!q) return !p;

        bool lflag = true;    

        if (p -> val == q -> val)
        {
            lflag = isSameTree(p -> left, q -> left);
            return lflag && isSameTree(p -> right, q -> right);
        }
        else
            return false;
    }
};