90 lines
2.5 KiB
C#
90 lines
2.5 KiB
C#
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var lines = File.ReadLines("input.txt");
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List<(long, List<long>)> equationList = new();
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foreach (var line in lines)
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{
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var splitLine = line.Split(":");
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var item1 = long.Parse(splitLine[0]);
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var item2 = splitLine[1].Split(" ").Where(x => x != String.Empty).Select(long.Parse).ToList();
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equationList.Add((item1, item2));
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}
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var part1 = EquationSolver(equationList, ['+', '*']);
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var part2 = EquationSolver(equationList, ['+', '*', '|']);
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Console.WriteLine($"Part1: {part1}\nPart2: {part2}");
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long EquationSolver(List<(long, List<long>)> equations, List<char> possibleOperators)
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{
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long numberOfPossibleEquations = 0;
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// For thread safety
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var lockObject = new object();
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Parallel.ForEach(equations, equation =>
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{
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var operatorCombinations = GetCombinations(possibleOperators.ToArray(), equation.Item2.Count - 1);
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var foundValidCombination = false;
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Parallel.ForEach(operatorCombinations, (operatorCombination, state) =>
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{
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if (!IsEquationPossible(equation.Item1, equation.Item2, operatorCombination)) return;
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lock (lockObject)
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{
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foundValidCombination = true;
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}
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state.Break();
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});
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if (!foundValidCombination) return;
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lock (lockObject)
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{
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numberOfPossibleEquations += equation.Item1;
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}
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});
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return numberOfPossibleEquations;
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}
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bool IsEquationPossible(long result, List<long> parameters, char[] operators)
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{
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var calculatedResult = parameters[0];
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for (var i = 0; i <= operators.Length - 1; i++)
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{
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calculatedResult = operators[i] switch
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{
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'+' => calculatedResult + parameters[i + 1],
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'*' => calculatedResult * parameters[i + 1],
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'|' => long.Parse($"{calculatedResult}{parameters[i + 1]}"),
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_ => throw new Exception("Invalid operator")
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};
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}
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return calculatedResult == result;
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}
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List<char[]> GetCombinations(char[] chars, int length)
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{
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var result = new List<char[]>();
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GenerateCombinations(chars, length, [], result);
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return result;
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}
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void GenerateCombinations(char[] chars, int length, List<char> current, List<char[]> result)
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{
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if (length == 0)
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{
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result.Add(current.ToArray());
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return;
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}
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foreach (var c in chars)
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{
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current.Add(c);
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GenerateCombinations(chars, length - 1, current, result);
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current.RemoveAt(current.Count - 1);
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}
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}
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