advent-of-code/2024/day-3/solution-2.sh

#!/usr/bin/env bash

# Filter out do(), don't(), and mul()
# then strip out tails to get do and don
# strip out mul() to get numbers
grep -Po 'do\(\)|don.t\(\)|mul\([0-9]+,[0-9]+\)' input |
  grep -Po 'don|do|mul\([0-9]+,[0-9]+\)' |
  sed -E 's/^mul\(([0-9]+),([0-9]+)\)/\1 \2/g' |
  awk '
    BEGIN {
      total = 0
      todo = 1
    }
    {
      if ($1 == "don") {
        todo = 0
      } else if ($1 == "do") {
        todo = 1
      } else if (todo == 1){
        total += $1 * $2 
      }
    }
    END {
      print total
    }'