private void Calculate()
{
var lo = ulong.Parse(fromBox.Text);
var hi = ulong.Parse(toBox.Text);
if (lo != _lo || hi != _hi) // Don't redraw if nothing changed
{
_lo = lo;
_hi = hi;
CollatzCalculator calculator = new CollatzCalculator();
_coords.Clear();
// Calculate for each seed and save result
Parallel.For((long)_lo, (long)_hi, seed =>
{
var entry = calculator.GetEntry((ulong)seed);
_coords.Add(entry);
});
_maxCount = _coords.Max(v => v.Count);
_maxPeak = _coords.Max(v => v.Peak);
}
}
static void Main()
{
try
{
Console.Write("Calculate up to? ");
long upper = long.Parse(Console.ReadLine());
CollatzCalculator calculator = new CollatzCalculator();
// Key is a particular peak value. Value is the number of sequences which have that peak value.
ConcurrentDictionary <ulong, ulong> peakFrequency = new ConcurrentDictionary <ulong, ulong>();
SequenceItem longest = new SequenceItem(0); // Item for head of sequence with longest count
SequenceItem highest = new SequenceItem(0); // Item for head of sequence with highest peak
object locker = new object();
Parallel.For(1, upper, seed =>
{
var entry = calculator.GetEntry((ulong)seed);
peakFrequency.AddOrUpdate(entry.Peak, 1, (k, v) => v + 1); // Incremen count for this peak
lock (locker)
{
// Check and update longest
if (entry.Count > longest.Count)
{
longest = entry;
}
// Check and update highest peak. In the event of a tie, choose the shortest sequence
if (entry.Peak > highest.Peak || entry.Peak == highest.Peak && entry.Count < highest.Count)
{
highest = entry;
}
}
});
Display(longest, "Longest sequence");
Console.WriteLine();
Display(highest, "Highest peak");
Console.WriteLine();
var mostFrequent = peakFrequency.OrderByDescending(p => p.Value).Take(3);
Console.WriteLine("Most common peaks (top 3):");
foreach (var pair in mostFrequent)
{
Console.WriteLine($" {pair.Key:N0} ({pair.Value:N0} occurrences).");
}
Console.WriteLine();
Console.WriteLine($"{calculator.AllocationCount:N0} numbers calculated with a peak value of {calculator.PeakValue:N0}.");
// Helper to display a full sequence
void Display(SequenceItem item, string label)
{
Console.WriteLine($"{label} with a seed up to {upper:N0} is for seed of {item.Current:N0} with {item.Count:N0} elements\n\tand with a peak value of {item.Peak:N0}.");
foreach (var entry in calculator.Sequence(item.Current))
{
Console.WriteLine($"{entry.Count:N0}: {entry.Current:N0} {(item.Peak == entry.Current ? "-- PEAK --" : "")}");
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.ReadLine();
}
