101. Symmetric Tree

Symmetric Tree

代码

public class Solution {
public boolean isSymmetric(TreeNode root) {
return helper(root, root);
}

public boolean helper(TreeNode m, TreeNode n){
if(m == null && n == null){
return true;
}
if(m == null || n == null){
return false;
}

return m.val == n.val && helper(m.left, n.right) && helper(m.right, n.left);
}
}