You can query the ReportServer database for this information, for example
SELECT CASE [Catalog].[Type] WHEN 1 THEN 'Folder' WHEN 2 THEN 'Report' WHEN 3 THEN 'Resource' WHEN 4 THEN 'Linked Report' WHEN 5 THEN 'Data Source' WHEN 6 THEN 'Report Model' WHEN 8 THEN 'Shared Dataset' WHEN 9 THEN 'Report Part' END AS CatalogType, [Catalog].[Type]
source share