|
| 1 | +# frozen_string_literal: true |
| 2 | + |
| 3 | +input=File.readlines(ARGV[0]) |
| 4 | + |
| 5 | +RULE=/^Step ([a-zA-Z]+) .* step ([a-zA-Z]+) can begin.$/.freeze |
| 6 | +input.map!{ |line|line.match(RULE).captures} |
| 7 | + |
| 8 | +dependents=input.group_by(&:first).transform_values{ |it|it.map(&:last)} |
| 9 | +dependencies=input.group_by(&:last).transform_values{ |it|it.map(&:first)} |
| 10 | + |
| 11 | +dependents.default_proc=proc{ |h,k|h[k]=[]} |
| 12 | +dependencies.default_proc=proc{ |h,k|h[k]=[]} |
| 13 | + |
| 14 | +steps_done=[] |
| 15 | +steps_current=dependents.keys.select{ |k|dependencies[k].empty?} |
| 16 | + |
| 17 | +whilesteps_done.size <dependencies.size |
| 18 | +steps_current.sort! |
| 19 | + |
| 20 | +next_task=steps_current.finddo |task| |
| 21 | +(dependencies[task] -steps_done).empty? |
| 22 | +end |
| 23 | + |
| 24 | +steps_done <<steps_current.delete(next_task) |
| 25 | +steps_current +=dependents[next_task] |
| 26 | +end |
| 27 | + |
| 28 | +putssteps_done.join |
