Swapping languages on CodinGame (a.k.a. system() calls)

Calling an interpreter from Bash

We can call different interpreters with a one-liner solution passed as a command-line parameter directly from bash.

Unfortunatelly, we need to escape any dollar signs $, double quotes " and backslashes \ in our source code (by adding a backslash \ before them). This would hurt especially in Perl and PHP, where all variable names start with a $ sign. Using single quote ' instead of double " in the bash invocation is better in these cases.

Note: All the examples provided would try to read the test cases as input. That would not work on Tech.io, therefore these coding examples are not runnable here. You can try them out in the CG IDE for the Rubik puzzle.

Base solution

My base solution for the sample puzzle is 34 characters long in Bash.

# ===== Bash
#   length = base [34] = 34 chars
read n;echo $((n>1?6*n*(n-2)+8:1))

Lua

# ===== to Lua from Bash
#   length = 8 + base [53] = 61 chars
lua -e"n=tonumber(io.read());print(n>1 and 6*n*(n-2)+8 or 1)"

My Lua solution is 53 chars. Calling the interpreter adds 12 chars.

Perl

# ===== to Perl from Bash
#   length = 9 + base [38] = 47 chars
perl -e'my$n=<STDIN>;print$n>1?6*$n*($n-2)+8:1'

My Perl solution is 38 chars. Calling the interpreter adds 9 chars.

PHP

# ===== to PHP from Bash
#   length = 8 + base [41] = 49 chars
php -r'$n=fgets(STDIN);echo$n>1?6*$n*($n-2)+8:1;'
# if we were using " then escaping would be needed for the $
php -r"\$n=fgets(STDIN);echo\$n>1?6*\$n*(\$n-2)+8:1;"

My PHP solution is 41 chars. Calling the interpreter adds 8 chars.

Python

# ===== to Python from Bash
#   length = 12 + base [47] = 59 chars
#   use python instead of python3 to invoke Python 2.x
python3 -c"n=int(input());print(6*n*(n-2)+8 if n>1 else 1)"

My Python solution is 47 chars. Calling the interpreter adds 12 chars. Here I did not need any escaping.

Note: using python instead of python3 saves 1 char, but it still invokes Python 2.x on CG, so your code might not be backwards compatible.

Ruby

# ===== to Ruby from Bash
#   length = 24 + base [34] = 58 chars
#   calling ruby without the full path no longer works...
/usr/local/bin/ruby -e"n=gets.to_i;puts n>1?6*n*(n-2)+8:1"

My Ruby solution is 34 chars. Currently ruby seems to be not in the $PATH on CG, so we need to add full path which costs 24 chars for invoking the interpreter.

Coming next...

Starting from bash is not always what we need. How to do similar system calls from other languages?