113 lines
2.8 KiB
C#
113 lines
2.8 KiB
C#
var diskMap = File.ReadAllText("input.txt");
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var disk = GenerateFileSystem(diskMap); // I could create a class for this, but... meh
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var part1 = DefragBlocks(new List<int>(disk.Item1));
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var part2 = DefragFiles(new List<int>(disk.Item1), new List<(int Id, int Length, int Position)>(disk.Item2), disk.Item3);
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Console.WriteLine($"Part1: {part1}\nPart2: {part2}");
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long DefragFiles(List<int> fileSystem, List<(int Id, int Length, int Position)> files, List<(int Length, int Position)> free)
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{
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for (var i = files.Count - 1; i >= 0; i--)
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{
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var file = files[i];
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for (var j = 0; j < free.Count; j++)
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{
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var slot = free[j];
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if (file.Position < slot.Position)
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{
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break;
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}
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if (slot.Length >= file.Length)
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{
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for (var k = 0; k < file.Length; k++)
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{
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(fileSystem[slot.Position + k], fileSystem[file.Position + k]) = (fileSystem[file.Position + k], fileSystem[slot.Position + k]);
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}
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free[j] = (slot.Length - file.Length, slot.Position + file.Length);
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break;
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}
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}
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}
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return CalculateChecksum(fileSystem);
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}
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long DefragBlocks(List<int> fileSystem)
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{
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(int left, int right) = (0, fileSystem.Count - 1);
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while (left < right)
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{
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if (fileSystem[left] != -1)
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{
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left++;
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}
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else
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{
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if (fileSystem[right] == -1)
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{
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right--;
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}
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else
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{
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(fileSystem[left], fileSystem[right]) = (fileSystem[right], fileSystem[left]);
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}
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}
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}
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return CalculateChecksum(fileSystem);
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}
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long CalculateChecksum(List<int> fileSystem)
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{
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var checksum = 0L;
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for (var i = 0; i < fileSystem.Count; i++)
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{
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var value = fileSystem[i];
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if (value != -1)
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{
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checksum += value * i;
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}
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}
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return checksum;
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}
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(List<int>, List<(int Id, int Length, int Position)>, List<(int Length, int Position)>) GenerateFileSystem(string diskMapDescription)
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{
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var file = true;
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var fileSystem = new List<int>();
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var freeSpace = new List<(int Length, int Position)>();
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var files = new List<(int Id, int Length, int Position)>();
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var id = 0;
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foreach (var length in diskMapDescription.Select(c => int.Parse(c + "")))
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{
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var value = file ? id : -1;
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var position = fileSystem.Count;
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if (file)
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{
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files.Add((id, length, position));
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id += 1;
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}
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else
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{
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freeSpace.Add((length, position));
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}
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for (int i = 0; i < length; i++)
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{
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fileSystem.Add(value);
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}
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file = !file;
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}
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return (fileSystem, files, freeSpace);
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} |