day08/parse_image.sh

   1 #!/bin/bash
   2
   3 exec 3<input.txt
   4
   5 declare -a layers
   6
   7 image_width=25
   8 image_height=6
   9
  10 layer_number=1
  11 while read -u 3 -N $((image_width*$image_height)) layer; do
  12     layers[$layer_number]=$layer
  13     layer_number=$((layer_number+1))
  14 done
  15
  16 echo "Got $layer_number layers"
  17
  18 get_count() {
  19     digit=$1
  20     data=$2
  21
  22     countstring="$(echo -n "$data" | sed -e 's#[^'$digit']##g;')"
  23     count=${#countstring}
  24
  25     echo $count
  26 }
  27
  28 zero_count_layer=0
  29 lowest_zero_count=-1
  30 for layer_number in ${!layers[@]}; do
  31     count=$(get_count 0 ${layers[$layer_number]})
  32     if [ $count -lt $lowest_zero_count ] || [ $lowest_zero_count -eq -1 ]; then
  33         lowest_zero_count=$count
  34         zero_count_layer=$layer_number
  35     fi
  36 done
  37
  38 one_count=$(get_count 1 ${layers[$zero_count_layer]})
  39 two_count=$(get_count 2 ${layers[$zero_count_layer]})
  40
  41 echo "Layer $zero_count_layer has the fewest zeros ($lowest_zero_count)"
  42 echo "Answer of number of 1s * number of 2s: $one_count * $two_count = $((one_count * two_count))"
  43
  44 draw_image() {
  45     image=""
  46     for (( y=0; y<$image_height; y++ )); do
  47         offset=$(($image_width*$y))
  48         for (( x=0; x<$image_width; x++ )); do
  49             for (( layer=1; layer<=$layer_number; layer++ )); do
  50                 data=${layers[$layer]}
  51                 case ${data:$((offset+x)):1} in
  52                     0)
  53                         image+=" "
  54                         continue 2
  55                         ;;
  56                     1)
  57                         image+="#"
  58                         continue 2
  59                         ;;
  60                 esac
  61             done
  62             image+="."
  63         done
  64     done
  65
  66     printf "=%.0s" {0..26}
  67     echo
  68     for (( y=0; y<$image_height; y++ )); do
  69         offset=$(($image_width*$y))
  70         echo "|${image:$offset:25}|"
  71     done
  72     printf "=%.0s" {0..26}
  73     echo
  74 }
  75
  76 draw_image