Codingame: Self-driving car testing

self-driving-car-testing.rb

## Detailed beginner solution ##
# Number of road patterns
n = gets.to_i
steering_commands = gets.chomp.split(';')
# Car position on the road first position is 1 and not 0
# That's why we need to substract 1
car_pos=steering_commands.shift.to_i-1
# We will build an array of all the steering instructions to apply
steering_per_turn=[]
steering_commands.each do |command_block|
    # Steering instruction is the last letter of the command block
    # If the block is "10S", steering is "S" and repeat is "10"
    steering=command_block[-1] 
    repeat=command_block.to_i
    # We converse the steering instruction in a number
    steering_numerical=case(steering)
    when 'S'
        0
    when 'L'
        -1
    when 'R'
        1
    end
    # We add the instruction the required number of times in the steering array
    repeat.times{ steering_per_turn<< steering_numerical }
end
STDERR.puts "Commands to execute: #{steering_per_turn.to_s}"

# For each road pattern
n.times do |i|
    qty,road = gets.chomp.split(';')
    # We execute the number of times the pattern is repeated
    qty.to_i.times do
        # New car position is previous position+new instruction
        car_pos += steering_per_turn.shift
        # Copy the road string
        line = road.dup
        # We place the car at the right position on the copied string
        line[car_pos] = '#'
        puts line
    end
end