Problem Statement
Pattern:
Solution
public boolean compare (TreeNode A, TreeNode B){
if(A == null && B == null) return true; // both null
if(A == null || B == null) return false; // one of them null
if(A.val != B.val) return false;
return compare(A.left, B.right) && compare(A.right, B.left);
}
public boolean isSymmetric(TreeNode root) {
if(root == null) return false;
return compare(root.left, root.right);
}Notes
- since symetric
compare(A.left, B.right) && compare(A.right, B.left)- mirror images