public static Object Solve()
{
InfiniteIntList.StartIndex = -999;
return(InfiniteIntList.Items.TakeWhile(a => a <= 999)
.SelectMany(a => InfiniteIntList.Items.TakeWhile(b => b <= 999)
.Select(b => new { a, b }))
.OrderByDescending(p => InfiniteIntList.GetItems(0).TakeWhile(n => (n * (p.a + n) + p.b).IsPrime())
.LastOrDefault())
.Select(p => p.a * p.b)
.First());
}
public static Object Solve()
{
InfiniteIntList.StartIndex = SmallestPerimeter;
return(InfiniteIntList.Items
.TakeWhile(p => p <= 1000)
.SelectMany(p => InfiniteIntList.GetItems(MinSideLength)
.TakeWhile(a => a <= MaxSideLength)
.SelectMany(a => InfiniteIntList.GetItems(MinSideLength)
.Skip((int)a)
.TakeWhile(b => b < (p - a) / 2)
.Select(b => new { p, a, b, c = p - b - a })))
.Where(x => Math.Pow(x.a, 2) + Math.Pow(x.b, 2) == Math.Pow(x.c, 2))
// Filter out duplicate entries
.GroupBy(x => x.p)
.OrderByDescending(group => group.Count())
.First()
.Key);
}
public static Object Solve()
{
// Build matrix in memory array
var matrix = matrixString.Split(' ').Select(x => Int64.Parse(x));
var solution = InfiniteIntList.GetItems(0, gridSize) // horizontal
.Take(gridSize)
.SelectMany(
r => InfiniteIntList.GetItems(r, 1)
.Take(gridSize - lineSize + 1)
.Select(
p => matrix.Skip((int)p)
.Take(4)
.Product()
)
)
.Concat(
InfiniteIntList.GetItems(0, gridSize) // diagonal (left to right)
.Take(gridSize - lineSize + 1)
.SelectMany(
r => InfiniteIntList.GetItems(r, 1)
.Take(gridSize - lineSize + 1)
.Select(
p => InfiniteIntList.GetItems(p, gridSize + 1)
.Take(4)
.Select(x => matrix.ElementAt((int)x))
.Product()
)
)
)
.Concat(
InfiniteIntList.GetItems(0, gridSize) // vertical
.Take(gridSize - lineSize + 1)
.SelectMany(
r => InfiniteIntList.GetItems(r, 1)
.Take(gridSize)
.Select(
p => InfiniteIntList.GetItems(p, gridSize)
.Take(4)
.Select(x => matrix.ElementAt((int)x))
.Product()
)
)
)
.Concat(
InfiniteIntList.GetItems(0, gridSize) // diagonal (right to left)
.Take(gridSize - lineSize + 1)
.SelectMany(
r => InfiniteIntList.GetItems(r + lineSize - 1, 1)
.Take(gridSize - lineSize + 1)
.Select(
p => InfiniteIntList.GetItems(p, gridSize - 1)
.Take(4)
.Select(x => matrix.ElementAt((int)x))
.Product()
)
)
)
.Max();
return(solution);
}
