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speed up day9
continuous-integration/drone/push Build is passing Details

This commit is contained in:
Ben Harris 2020-12-09 15:55:56 -05:00
parent de1f5edf78
commit 4f7a18525c
2 changed files with 22 additions and 14 deletions
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2
aoc2020/Day.cs
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@ -18,7 +18,7 @@ namespace aoc2020
File.ReadLines(FileName);
protected string FileName =>
Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"input/day{DayNumber,2:0#}.in");
Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"input/day{DayNumber,2:00}.in");
public abstract string Part1();
public abstract string Part2();

34
aoc2020/Day09.cs
View File

@ -17,25 +17,33 @@ namespace aoc2020
public override string Part1()
{
var i = 25;
while (_list.Skip(i - 25).Take(25).Combinations(2).Select(c => c.Sum()).Contains(_list[i])) i++;
_part1 = _list[i];
return $"{_list[i]}";
for (var i = 25; i < _list.Length - 25; i++)
{
var preamble = _list[(i - 25)..i];
if (!preamble.Any(num1 => preamble.Any(num2 => num1 + num2 == _list[i])))
{
_part1 = _list[i];
return $"{_part1}";
}
}
return "";
}
public override string Part2()
{
for (var i = 0; i < _list.Length - 1; i++)
for (var i = 0; i < _list.Length; i++)
{
var offset = 1;
while (_list.Skip(i).Take(offset).Sum() < _part1) offset++;
long sum = 0;
for (var j = i; j < _list.Length; j++)
{
sum += _list[j];
if (sum > _part1) break;
if (sum != _part1) continue;
var subset = _list.Skip(i).Take(offset).ToArray();
if (subset.Sum() != _part1) continue;
var min = subset.Min();
var max = subset.Max();
return $"{min + max}";
var subset = _list[i..(j + 1)].ToArray();
return $"{subset.Min() + subset.Max()}";
}
}
return "";