day07/crabs.sh

   1 #!/bin/bash
   2
   3 set -u
   4
   5 filename="${1:-example.txt}"
   6
   7 exec 3<"$filename"
   8
   9 OLDIFS="$IFS"
  10 IFS=","
  11 read -u 3 -a crabs
  12
  13 IFS=$'\n'
  14 crabs=($(sort -n <<<"${crabs[*]}"))
  15
  16 mid_point=$((${#crabs[@]} / 2))
  17 mid_val=${crabs[$mid_point]}
  18
  19 fuel=0
  20
  21 for (( a=0; a<${#crabs[@]}; a++ )); do
  22     diff=$((mid_val-${crabs[$a]}))
  23     diff=${diff#-}
  24     ((fuel+=$diff))
  25 done
  26
  27 echo "Fuel needed: $fuel"