day10/zap.sh

   1 #!/bin/bash
   2
   3 basedir=$(dirname $(readlink -f $BASH_SOURCE))
   4 . $basedir/common.sh
   5
   6 our_asteroid=26,29
   7
   8 declare -A asteroids
   9 declare -A asteroid_angles
  10
  11 read_file input.txt
  12
  13 # calculate angles to each asteroid from us
  14 for asteroid in ${!asteroids[@]}; do
  15     if [ $asteroid == $our_asteroid ]; then
  16         continue
  17     fi
  18
  19     # otherwise, get the angle from us to there
  20     angle=$(get_angle $our_asteroid $asteroid)
  21
  22     # see if we've already got this angle as a key, if so append to it,
  23     # otherwise set it
  24     if [ ${asteroid_angles[$angle]+a} ]; then
  25         asteroid_angles[$angle]+="|$asteroid"
  26     else
  27         asteroid_angles[$angle]=$asteroid
  28     fi
  29 done
  30
  31 zapped_count=0
  32
  33 sorted_angles=( "$(get_angles_list asteroid_angles)" )
  34
  35 for (( round=0; round<3; round++ )); do
  36     for angle in $sorted_angles; do
  37         if [ ${asteroid_angles[$angle]+a} ]; then
  38             echo "$angle: ${asteroid_angles[$angle]}"
  39             closest=$(get_closest_asteroid "${asteroid_angles[$angle]}")
  40             #echo "      - closest $closest"
  41             # blow up the closest!
  42             newlist=$(remove_asteroid_from_string ${asteroid_angles[$angle]} $closest)
  43             if [ "x$newlist" == "x" ]; then
  44                 unset asteroid_angles[$angle]
  45             else
  46                 asteroid_angles[$angle]=$newlist
  47             fi
  48             zapped_count=$((zapped_count+1))
  49
  50             echo "$zapped_count: $closest"
  51
  52             if [ $zapped_count -eq 200 ]; then
  53                 echo "The 200th asteroid to be zapped was $closest"
  54                 break 2
  55             fi
  56         fi
  57     done
  58 done
  59
  60 echo "And we're done."