So bitcoin uses sha256, litecoin scrypt, dash x11.
Where is revision location(source code filename, approx line position) of this algorithm?
Simply google. Those algorithms (SHA, scrypt) weren't invented for those cryptocurrencies.
They existed before.
SHA:
https://en.wikipedia.org/wiki/SHA-2scrypt:
https://en.wikipedia.org/wiki/ScryptX11 is concatenated algorithm composed of BLAKE, BMW, Grøstl, JH, Keccak, Skein, Luffa, CubeHash, SHAvite, SIMD and Echo.
How change to x11 algorithm? Some site says x11 is best algorithm.
Changing the algorithm would require a hard fork (
https://en.wikipedia.org/wiki/Fork_(blockchain)#Hard_fork).
There is no "best" algorithm.
Simply because there is no definition of a "best" algorithm.
Additionally you should not believe what you read on "some site".