day10/syntax_check.sh

   1 #!/bin/bash
   2
   3 set -u
   4
   5 filename="${1:-example.txt}"
   6 exec 3<"$filename"
   7
   8 declare -a brackets
   9
  10 line_number=0
  11 score=0
  12 completion_score=0
  13
  14 declare -A bracket_scores=( [")"]=3 ["]"]=57 ["}"]=1197 [">"]=25137 )
  15 declare -A bracket_complete_score=( [")"]=1 ["]"]=2 ["}"]=3 [">"]=4 )
  16 declare -a completion_scores
  17
  18 while read -u 3 line; do
  19     ((line_number+=1))
  20     bad_line=0
  21     for (( a=0; a<${#line}; a++ )); do
  22         char=${line:$a:1}
  23         case $char in
  24             "(")
  25                 brackets+=(")")
  26                 ;;
  27             "<")
  28                 brackets+=(">")
  29                 ;;
  30             "[")
  31                 brackets+=("]")
  32                 ;;
  33             "{")
  34                 brackets+=("}")
  35                 ;;
  36             *)
  37                 if [ $char != ${brackets[-1]} ]; then
  38                     echo "Syntax error, bracket: $char, expected ${brackets[-1]} at offset $a on line $line_number"
  39                     ((score+=${bracket_scores[$char]}))
  40                     brackets=()
  41                     bad_line=1
  42                     # we're now skipping the rest of the line
  43                     continue 2
  44                 else
  45                     # all good, so remove the last element of the array
  46                     unset brackets[-1]
  47                 fi
  48                 ;;
  49         esac
  50     done
  51     if [ $bad_line -eq 0 ]; then
  52         incomplete_lines+=("$line")
  53         completion_score=0
  54         # usefully, brackets will still contain the right things
  55         while [ ${#brackets[@]} -gt 0 ]; do
  56             ((completion_score*=5))
  57             ((completion_score+=${bracket_complete_score[${brackets[-1]}]}))
  58             unset brackets[-1]
  59         done
  60         completion_scores+=($completion_score)
  61     fi
  62 done
  63
  64 echo "Score for file: $score"
  65
  66 # sort completion_scores
  67 IFS=$'\n'
  68 completion_scores=($(sort -n <<<"${completion_scores[*]}"))
  69 # now get the middle value
  70 mid_completion=$((${#completion_scores[@]} / 2))
  71 echo "Completion score: ${completion_scores[$mid_completion]}"