31 lines
783 B
C#
31 lines
783 B
C#
namespace AOC2015;
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/// <summary>
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/// Day 25: <a href="https://adventofcode.com/2015/day/25"/>
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/// </summary>
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public sealed partial class Day25() : Day(2015, 25, "Let It Snow")
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{
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[GeneratedRegex(@"\d+")]
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private static partial Regex NumbersRegex();
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private int _row, _col;
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public override void ProcessInput()
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{
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var s = NumbersRegex().Matches(Input.First()).Select(m => int.Parse(m.Value)).ToList();
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_row = s[0];
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_col = s[1];
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}
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public override object Part1()
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{
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var index = _row + _col - 2;
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index = index * (index + 1) / 2 + _col - 1;
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return Enumerable.Range(0, index)
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.Aggregate(20151125ul, (current, _) => current * 252533 % 33554393);
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}
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public override object Part2() => "";
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}
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