951. Flip Equivalent Binary Trees

public class TreeNode
{
    public int val;
    public TreeNode left;
    public TreeNode right;
    public TreeNode(int val = 0, TreeNode left = null, TreeNode right = null)
    {
        this.val = val;
        this.left = left;
        this.right = right;
    }
}

public class Solution
{
    public bool FlipEquiv(TreeNode root1, TreeNode root2)
    {
        if (root1 == null)
            return root2 == null;
        if (root2 == null)
            return root1 == null;
        if (root1.val != root2.val)
            return false;
        return //
            FlipEquiv(root1.left, root2.left) && FlipEquiv(root1.right, root2.right) ||
            FlipEquiv(root1.left, root2.right) && FlipEquiv(root1.right, root2.left);
    }
}