Same Tree (二叉树DFS)

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

两颗二叉树完全相同，也就是某个节点的左右孩子，和另外一棵树的的对应节点的左右孩子相等。和镜像对称树那题类似。

代码：

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