76 lines
2.8 KiB
C#
76 lines
2.8 KiB
C#
using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using AdvenOfCode.Contracts;
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using Coordinate = (int x, int y);
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namespace AoC_2025;
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public class Day06 : IPuzzleSolver<long>
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{
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private (string[] operands, string[] numbers) ParsePuzzleInput(string path)
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{
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var puzzleInput = File.ReadAllLines(path)
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.Where(line => !string.IsNullOrWhiteSpace(line))
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.ToArray();
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var operands = puzzleInput[^1]
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.Split(' ', StringSplitOptions.RemoveEmptyEntries);
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var numbers = puzzleInput[..^1];
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return (operands, numbers);
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}
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public long SolvePart1(string pathToPuzzleInput)
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{
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var calculations = ParsePuzzleInput(pathToPuzzleInput);
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var numbers = calculations.numbers
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.Select(line => line.Split(' ', StringSplitOptions.RemoveEmptyEntries))
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.Select(line => line.Index())
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.SelectMany(tuples => tuples.Select(tuple => (tuple.Index, long.Parse(tuple.Item))))
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.ToArray();
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var pivotedNumbers = numbers.GroupBy(tuple => tuple.Index);
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var indexedOperands = calculations.operands
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.Index()
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.Select(tuple => (tuple.Index, ParseOperand(tuple.Item)))
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.ToDictionary();
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var results = pivotedNumbers.Select(group =>
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group
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.Select(tuple => tuple.Item2)
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.Aggregate(indexedOperands[group.Key].opBaseValue,
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(acc, number) => indexedOperands[group.Key].operation(acc, number)));
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return results.Sum();
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}
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public long SolvePart2(string pathToPuzzleInput)
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{
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var calculations = ParsePuzzleInput(pathToPuzzleInput);
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var operands = calculations.operands.Select(ParseOperand).Reverse().ToArray();
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List<List<long>> numberColumns = [];
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List<long> currentColumn = [];
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for (var i = 1; i <= calculations.numbers[0].Length; i++)
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{
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var current = calculations.numbers.Aggregate("", (current1, number) => current1 + number[^i]);
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if (!string.IsNullOrWhiteSpace(current))
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{
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currentColumn.Add(long.Parse(current));
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}
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else
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{
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numberColumns.Add(currentColumn);
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currentColumn = [];
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}
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}
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numberColumns.Add(currentColumn);
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return numberColumns
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.Select((column, colIndex) => column.Aggregate(operands[colIndex].opBaseValue, (acc, next) => operands[colIndex].operation(acc, next)))
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.Sum();
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}
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private (Func<long, long, long> operation, long opBaseValue) ParseOperand(string operand) => operand switch
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{
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"+" => ((long a, long b) => a + b, 0),
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"*" => ((long a, long b) => a * b, 1),
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_ => throw new ArgumentOutOfRangeException(nameof(operand))
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};
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} |