# 101. Symmetric Tree

## 刷题内容

• https://leetcode.com/problems/symmetric-tree/

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree [1,2,2,3,4,4,3] is symmetric:

1
/ \
2   2
/ \ / \
3  4 4  3
But the following [1,2,2,null,3,null,3] is not:
1
/ \
2   2
\   \
3    3


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˼· **- ʱ�临�Ӷ�: O(N)*- �ռ临�Ӷ�: O(1)***

/**
* 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 judge(TreeNode* oTree,TreeNode* mTree){
if((oTree != nullptr) && (mTree != nullptr))
{
if((oTree ->val == mTree  ->val) && (oTree ->val == mTree ->val))
return judge(oTree ->left,mTree ->right) && judge(oTree ->right,mTree ->left);
return false;
}
if(oTree == mTree)
return true;
return false;
}
bool isSymmetric(TreeNode* root) {
if(root != nullptr)
return judge(root ->left,root ->right);
return true;
}
};


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