________________________________________________________________________

This file is part of Logtalk <https://logtalk.org/>  
SPDX-FileCopyrightText: 1998-2023 Paulo Moura <pmoura@logtalk.org>  
SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
________________________________________________________________________


To load this example and for sample queries, please see the `SCRIPT.txt`
file.

This folder contains a Logtalk solution for the Advent of Code 2023 Day 1
problem:

https://adventofcode.com/2023/day/1

The solution provided is for Part 2 of the problem. To solve just for
Part 1, comment out the grammar rules for digits as letters.

Copy of the problem description:

> --- Part One ---
> 
> You try to ask why they can't just use a weather machine ("not powerful
> enough") and where they're even sending you ("the sky") and why your map
> looks mostly blank ("you sure ask a lot of questions") and hang on did
> you just say the sky ("of course, where do you think snow comes from")
> when you realize that the Elves are already loading you into a trebuchet
> ("please hold still, we need to strap you in").
> 
> As they're making the final adjustments, they discover that their
> calibration document (your puzzle input) has been amended by a very
> young Elf who was apparently just excited to show off her art skills.
> Consequently, the Elves are having trouble reading the values on the
> document.
> 
> The newly-improved calibration document consists of lines of text; each
> line originally contained a specific calibration value that the Elves
> now need to recover. On each line, the calibration value can be found
> by combining the first digit and the last digit (in that order) to form
> a single two-digit number.
> 
> For example:
> 
> 1abc2
> pqr3stu8vwx
> a1b2c3d4e5f
> treb7uchet
> 
> In this example, the calibration values of these four lines are
> 12, 38, 15, and 77. Adding these together produces 142.
> 
> Consider your entire calibration document. What is the sum of all
> of the calibration values?
> 
> --- Part Two ---
> 
> Your calculation isn't quite right. It looks like some of the digits are
> actually spelled out with letters: one, two, three, four, five, six, seven,
> eight, and nine also count as valid "digits".
> 
> Equipped with this new information, you now need to find the real first
> and last digit on each line. For example:
> 
> two1nine
> eightwothree
> abcone2threexyz
> xtwone3four
> 4nineeightseven2
> zoneight234
> 7pqrstsixteen
> In this example, the calibration values are 29, 83, 13, 24, 42, 14, and 76.
> Adding these together produces 281.
