-
Notifications
You must be signed in to change notification settings - Fork 0
/
SymmetricTree.cpp
41 lines (39 loc) · 975 Bytes
/
SymmetricTree.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
/*
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
For example, this binary tree is symmetric:
1
/ \
2 2
/ \ / \
3 4 4 3
But the following is not:
1
/ \
2 2
\ \
3 3
Note:
Bonus points if you could solve it both recursively and iteratively.
*/
/**
* 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 dfs(TreeNode *left,TreeNode *right)
{
if(!left && !right) return true;
if((left && !right) || (!left && right) || (left->val!=right->val)) return false;
return dfs(left->left,right->right) && dfs(left->right,right->left);
}
bool isSymmetric(TreeNode* root) {
if(root==NULL || (!root->left && !root->right)) return true;
return dfs(root->left,root->right);
}
};