Please implement a function, a binary tree is used to determine not symmetrical. If a binary tree and its image, as it is symmetrical.
For example, a binary tree [1,2,2,3,4,4,3] is symmetric.
1
/ \
22
/ \ / \
3443
but the following [1,2,2, null, 3, null , 3] is not a mirror image:
1
/ \
2 2
\ \
3 3
Example 1:
Input: root = [1,2,2,3,4,4,3]
Output: true
Example 2:
Input: root = [1,2,2, null, 3, null, 3]
Output: false
limit:
0 <= the number of nodes <= 1000
Code:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public boolean isSymmetric(TreeNode root) {
if(root==null)
{
return true;
}
if(root.left==null&&root.right==null)
{
return true;
}
if(root.left==null||root.right==null)
{
return false;
}
return find(root.left,root.right);
}
public boolean find(TreeNode p,TreeNode q)
{
if(p==null&&q==null)
{
return true;
}
if(p==null||q==null)
{
return false;
}
if(p.val==q.val)
{
return find(p.left,q.right)&&find(p.right,q.left);
}
else
{
return false;
}
}
}
