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Save another 30% or so part 2 perf

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This is really dipping into "sacrifice programming convenience for performance" territory, but the savings are nice enough that I'll sacrifice a bit here. This drops my 50ms part 2 to more like 34ms.
This commit is contained in:
Chris Pickett
2021-12-15 13:28:53 -06:00
parent 84c7f424ba
commit eeed2bbdd3
1 changed files with 18 additions and 23 deletions
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41
src/15.cs
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@ -19,25 +19,15 @@ internal class Day15 : Day
Part2(grid); Part2(grid);
} }
private static IEnumerable<(int x, int y)> Adjacent(byte[,] grid, int i, int j) private static readonly (int x, int y)[] Neighbors =
{ {
if (i > 0) (-1, 0),
{ ( 0, -1),
yield return (i - 1, j); ( 1, 0),
} ( 0, 1),
if (j > 0) };
{
yield return (i, j - 1); private static bool IsValidPoint(byte[,] grid, int x, int y) => x >= 0 && x < grid.GetLength(0) && y >= 0 && y < grid.GetLength(1);
}
if (i < grid.GetLength(0) - 1)
{
yield return (i + 1, j);
}
if (j < grid.GetLength(1) - 1)
{
yield return (i, j + 1);
}
}
private static int Solve(byte[,] riskMap) private static int Solve(byte[,] riskMap)
{ {
@ -60,13 +50,18 @@ internal class Day15 : Day
for (var currPoint = start; currPoint != end; currPoint = q.Dequeue()) for (var currPoint = start; currPoint != end; currPoint = q.Dequeue())
{ {
foreach (var adjacent in Adjacent(riskMap, currPoint.x, currPoint.y)) foreach (var adjacent in Neighbors)
{ {
var totalRiskThroughP = totalRiskMap[currPoint.x, currPoint.y] + riskMap[adjacent.x, adjacent.y]; var (x, y) = (currPoint.x + adjacent.x, currPoint.y + adjacent.y);
if (totalRiskThroughP < totalRiskMap[adjacent.x, adjacent.y]) if (!IsValidPoint(riskMap, x, y))
{ {
totalRiskMap[adjacent.x, adjacent.y] = totalRiskThroughP; continue;
q.Enqueue(adjacent, totalRiskThroughP); }
var totalRiskThroughP = totalRiskMap[currPoint.x, currPoint.y] + riskMap[x, y];
if (totalRiskThroughP < totalRiskMap[x, y])
{
totalRiskMap[x, y] = totalRiskThroughP;
q.Enqueue((x, y), totalRiskThroughP);
} }
} }
} }