AOC2019day6part2

6-2.sh

#!/bin/bash

set -eu
set -o pipefail

orrery=/dev/shm/orrery

rm -rf "$orrery"
mkdir "$orrery"

orbits=($(< "$1"))

for orbit in "${orbits[@]}"; do
  inner=${orbit%)*}
  outer=${orbit#*)}
  innerdir=$(find "$orrery" -name "$inner")
  outerdir=$(find "$orrery" -name "$outer")
  if [ -z "$innerdir" ]; then
    mkdir "$orrery/$inner"
    innerdir=$orrery/$inner
  fi

  if [ -z "$outerdir" ]; then
    mkdir "$innerdir/$outer"
  else
    mv "$outerdir" "$innerdir"/
  fi
done

comm -3 <(find "$orrery" -name YOU -printf %P\\n|tr / \\n|sort) \
        <(find "$orrery" -name SAN -printf %P\\n|tr / \\n|sort) \
  | grep -cvE '^\s*(YOU|SAN)\s*$'