prblm101.java

public class prblm101 {
    public static void main(String[] args) {
        TreeNode root = new TreeNode(1);
        root.left = new TreeNode(2);
        root.right = new TreeNode(2);
        root.left.left = new TreeNode(3);
        root.left.right = new TreeNode(4);
        root.right.left = new TreeNode(4);
        root.right.right = new TreeNode(3);

        System.out.println(new prblm101().isSymmetric(root));
    }

    public boolean isSymmetric(TreeNode root) {
        return solve(root.left, root.right);
    }

    public boolean solve(TreeNode p, TreeNode q) {
        if(p == null && q == null) return true;
        if(p == null || q == null) return false;
        if(p.val != q.val) return false;
        return solve(p.left, q.right) && solve(p.right, q.left);
    }
}