There are different directories in which there are some solved problems from different sites
In this directory there are problems solved divided in which contest they were
Some problems from the CSES site
Some problems from OII (Olimpiadi italiane dell'informatica)
In this directory there are some util data structure
In this directory there are different sub-directories in which there are problems solved from different categories of USACO (Bronze, Silve, Gold, Platinum)