It is very strange, but actually D-CLANG solutions is slower than D-DMD solutions, since ldc2 is known as strong optimization compiler. And on my home computer ldc2 is about 1.5 times faster than dmd if both sources were compiled with -O flags and ldc2 is slower when sources were compiled without -O. So my guess is that SPOJ doesn’t use optimization flags for D compilers.
I also want to mention that without optimization/release flags code can run 5 times slower.
So, please, add these optimization options -O -release -boundscheck=off to D-DMD and D-CLANG compilers.
And these -O2 -frelease to D (GDC), since there are some problems like Count on Tree for which only available D compiler is GDC (actually the most slowest) and time limits are very tight.
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