66 lines
1.9 KiB
C#
66 lines
1.9 KiB
C#
using System.Collections.Concurrent;
|
|
using System.Numerics;
|
|
using PeterO.Numbers;
|
|
|
|
namespace PerfectNumbers.Core;
|
|
|
|
public static class PowerCache
|
|
{
|
|
private static readonly ConcurrentDictionary<ulong, BigInteger[]> BigCache = new();
|
|
private static readonly ConcurrentDictionary<EInteger, EInteger[]> ECache = new();
|
|
|
|
public static BigInteger Get(ulong baseVal, int exponent)
|
|
{
|
|
if (!BigCache.TryGetValue(baseVal, out var powers))
|
|
{
|
|
powers = new BigInteger[exponent + 1];
|
|
powers[0] = BigInteger.One;
|
|
BigCache[baseVal] = powers;
|
|
}
|
|
|
|
if (powers.Length <= exponent)
|
|
{
|
|
int oldLength = powers.Length;
|
|
Array.Resize(ref powers, exponent + 1);
|
|
for (int i = oldLength; i <= exponent; i++)
|
|
powers[i] = BigInteger.Zero;
|
|
|
|
BigCache[baseVal] = powers;
|
|
}
|
|
|
|
if (powers[exponent].IsZero)
|
|
{
|
|
for (int i = 1; i <= exponent; i++)
|
|
if (powers[i].IsZero)
|
|
powers[i] = powers[i - 1] * baseVal;
|
|
}
|
|
|
|
return powers[exponent];
|
|
}
|
|
|
|
public static EInteger Get(EInteger baseVal, int exponent)
|
|
{
|
|
if (!ECache.TryGetValue(baseVal, out var powers))
|
|
{
|
|
powers = new EInteger[exponent + 1];
|
|
powers[0] = EInteger.One;
|
|
ECache[baseVal] = powers;
|
|
}
|
|
if (powers.Length <= exponent)
|
|
{
|
|
int oldLength = powers.Length;
|
|
Array.Resize(ref powers, exponent + 1);
|
|
for (int i = oldLength; i <= exponent; i++)
|
|
powers[i] = null;
|
|
ECache[baseVal] = powers;
|
|
}
|
|
if (powers[exponent] == null)
|
|
{
|
|
for (int i = 1; i <= exponent; i++)
|
|
if (powers[i] == null)
|
|
powers[i] = powers[i - 1]! * baseVal;
|
|
}
|
|
return powers[exponent]!;
|
|
}
|
|
}
|