Leetcode: Same Tree

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.

刚开始的题都很简单。

/**
 * 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 (p == NULL && q == NULL) {
            return true;
        }
        if (p == NULL && q != NULL || p != NULL && q == NULL) {
            return false;
        }
        
        return (p->val == q->val && 
                isSameTree(p->left, q->left) && 
                isSameTree(p->right, q->right));
    }
};

==========================第二次=======================

/** * 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 (p == NULL && q == NULL) {            return true;        }        else if (p == NULL || q == NULL) {            return false;        }                if (p->val != q->val) {            return false;        }        else {            return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);        }    }};