LeetCode之Same Tree

题意：

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.

给定两个二叉树,编写一个函数来检查是否他们是相等的。 　　 　　

两个二叉树,如果他们被认为是相等的,在结构上是相同的,节点有相同的值。

解题思路：递归！递归比较每个节点的左子树和右子树以及该节点的值，返回三个结果的与运算结果！

C代码：

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     struct TreeNode *left;
*     struct TreeNode *right;
* };
*/
bool isSameTree(struct TreeNode* p, struct TreeNode* q) {
if(p == NULL && q == NULL) return true;
else if(p == NULL || q == NULL) return false;
return p->val == q->val && isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
}

C++代码：

/**
* Definition for a binary tree node.
* 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;
return p->val == q->val && isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
}
};

Java代码：

/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if(p == null && q == null) return true;
else if(p == null || q == null) return false;
return isSameTree(p.left, q.left) && isSameTree(p.right, q.right) && p.val == q.val;
}
}