One thing that Code Jam does differently (and imho better) is that they give you an input set and you have 8 minutes (or so) to upload the solution. This is expected to give more than enough space for language speed variance.
Instead of execution time, coding time is much more precious in such competitions, and
Micro-optimizing has it's place, but it's usually not in a programming competition. that's what using ruby instead of C gives you leverage for that, as you can express more complex ideas and algorithms more easily (which should be the focus point).
This doesn't mean you shouldn't know the cost of operations.
Coding time was actually not precious here. They gave about a day to do the qualification round but only eight minutes to run your program once you downloaded the input data, so the round was optimized for writing highly performant code at your leisure and then downloading the data when you are all set to go.
That's because most contests (but not all) are limited to C, C++ and Java and they've practiced hundreds if not thousands of hours on solving those kinds of problems.
Of course they will be more efficient in c++ than a person who is spending most of their time wondering how costly string operations are.
That doesn't mean that there aren't also people who have done the same and still prefer python (or some other language) not for execution, but development speed (and bignum, larger standard library...)
One thing that Code Jam does differently (and imho better) is that they give you an input set and you have 8 minutes (or so) to upload the solution. This is expected to give more than enough space for language speed variance.
Instead of execution time, coding time is much more precious in such competitions, and
Micro-optimizing has it's place, but it's usually not in a programming competition. that's what using ruby instead of C gives you leverage for that, as you can express more complex ideas and algorithms more easily (which should be the focus point).
This doesn't mean you shouldn't know the cost of operations.