First i had WA 20, because of wrong apporach, now WA 26...
Maybe somebody have some test ar now something similar to this testcase.

Btw, I am using dijkstra from source to sink with backegde cost of zero. Or this is also wrong?

I was getting WA26 when use this declaration for "INFINITE" constant:

const __int64 INF = (__int64)1e17;

... when I change it for next one:

const __int64 INF = 10000....... ;

I get AC!