day07/crabs2.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 count=$((${#crabs[@]}))
  17 total=0
  18 for elem in "${crabs[@]}"; do
  19     ((total+=$elem))
  20 done
  21 mean=$((total / $count))
  22
  23 fuel=0
  24
  25 # Actual best position could be mean +- 1, so loop through them to check
  26 for (( tempmean=$((mean-1)); tempmean<=$((mean+1)); tempmean++ )); do
  27     new_fuel=0
  28     for (( a=0; a<${#crabs[@]}; a++ )); do
  29         diff=$((tempmean-${crabs[$a]}))
  30         diff=${diff#-}
  31         if [ $diff -gt 0 ]; then
  32             for (( i=0; i<=$diff; i++ )); do
  33                 ((new_fuel+=$i))
  34             done
  35         fi
  36     done
  37     if [ $fuel -eq 0 ] || [ $new_fuel -lt $fuel ]; then
  38         fuel=$new_fuel
  39         found_mean=$tempmean
  40     fi
  41 done
  42
  43 echo "Found mean: $found_mean"
  44 echo "Fuel needed: $fuel"