aoc/2023/1/2/solution.sh

#!/usr/bin/env bash

set -o errexit
set -o nounset
set -o pipefail
if [[ "${TRACE-0}" == "1" ]]; then
  set -o xtrace
fi

INPUT=$1

main ()
{
  digit_regex="[[:digit:]]|one|two|three|four|five|six|seven|eight|nine"
  digit_regex_reverse="[[:digit:]]|eno|owt|eerht|ruof|evif|xis|neves|thgie|enin"
  declare -A digits=([one]=1 [two]=2 [three]=3 [four]=4 [five]=5 [six]=6 [seven]=7 [eight]=8 [nine]=9)
  declare -a components
  declare -i result=0
  while read -r line; do
    first=$(grep -E -o "${digit_regex}" <<< "${line}" | head -n 1)
    last=$(rev <<< "${line}" | grep -E -o "${digit_regex_reverse}" | rev | head -n 1)
    first=$([[ ! ${first} =~ ^[0-9]$ ]] && echo "${digits[${first}]}" || echo "${first}")
    last=$([[ ! ${last} =~ ^[0-9]$ ]] && echo "${digits[${last}]}" || echo "${last}")
    components+=("${first}${last}")
  done < "${INPUT}"
  for value in "${components[@]}"; do
    (( result += value ))
  done
  echo "${result}"
}

main