44 lines
1.4 KiB
C#
44 lines
1.4 KiB
C#
using System;
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using System.Linq;
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using System.Numerics;
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namespace LahNumbers {
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class Program {
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static BigInteger Factorial(BigInteger n) {
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if (n == 0) return 1;
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BigInteger res = 1;
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while (n > 0) {
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res *= n--;
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}
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return res;
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}
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static BigInteger Lah(BigInteger n, BigInteger k) {
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if (k == 1) return Factorial(n);
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if (k == n) return 1;
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if (k > n) return 0;
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if (k < 1 || n < 1) return 0;
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return (Factorial(n) * Factorial(n - 1)) / (Factorial(k) * Factorial(k - 1)) / Factorial(n - k);
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}
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static void Main() {
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Console.WriteLine("Unsigned Lah numbers: L(n, k):");
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Console.Write("n/k ");
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foreach (var i in Enumerable.Range(0, 13)) {
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Console.Write("{0,10} ", i);
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}
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Console.WriteLine();
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foreach (var row in Enumerable.Range(0, 13)) {
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Console.Write("{0,-3}", row);
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foreach (var i in Enumerable.Range(0, row + 1)) {
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var l = Lah(row, i);
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Console.Write("{0,11}", l);
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}
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Console.WriteLine();
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}
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Console.WriteLine("\nMaximum value from the L(100, *) row:");
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var maxVal = Enumerable.Range(0, 100).Select(a => Lah(100, a)).Max();
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Console.WriteLine(maxVal);
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}
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}
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}
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