leetcode_same tree_easy

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.

直接DFS，遞歸調用判斷就好，注意邊界和遞歸返回即可。

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode *p, TreeNode *q) {
        if(NULL==p && NULL==q)
            return true;
        else if(NULL!=p&&NULL!=q)
        {
            if(p->val!=q->val)
                return false;
            else
                return isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);
        }
        else
            return false;
    }
};