day 4
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06316af729
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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namespace aoc2019
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{
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internal class Day4 : Day
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{
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int start, end;
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public Day4()
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{
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var range = File.ReadLines("input/day4.in")
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.First()
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.Split('-')
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.Select(i => int.Parse(i))
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.ToList();
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start = range[0]; end = range[1];
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}
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private bool IsValid(int i)
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{
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return Math.Floor(Math.Log10(i) + 1) == 6
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&& i >= start
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&& i <= end
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&& IsIncreasingDigits(i);
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}
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private bool IsIncreasingDigits(int i)
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{
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int prev = 0;
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bool hasDup = false;
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foreach (var c in i.ToString())
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{
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int curr = c - '0';
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if (curr < prev)
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return false;
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if (curr == prev)
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hasDup = true;
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prev = curr;
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}
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return hasDup;
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}
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private bool Part2Criterion(int i)
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{
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var s = i.ToString();
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return s.Select(c => s.Count(j => j == c)).Any(c => c == 2);
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}
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public override void Part1()
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{
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Console.WriteLine(Enumerable.Range(start, end).Count(i => IsValid(i)));
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}
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public override void Part2()
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{
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Console.WriteLine(Enumerable.Range(start,end).Count(i => IsValid(i) && Part2Criterion(i)));
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}
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}
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}
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@ -11,8 +11,9 @@ namespace aoc2019
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case 1: return new Day1();
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case 2: return new Day2();
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case 3: return new Day3();
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case 4: return new Day4();
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default: return null;
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}
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}
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}
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}
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}
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@ -15,6 +15,9 @@
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<None Update="input\day3.in">
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<CopyToOutputDirectory>Always</CopyToOutputDirectory>
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</None>
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<None Update="input\day4.in">
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<CopyToOutputDirectory>Always</CopyToOutputDirectory>
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</None>
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</ItemGroup>
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</Project>
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@ -0,0 +1 @@
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245318-765747
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