31 lines
901 B
C#
31 lines
901 B
C#
using System;
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using System.Numerics;
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static class Program
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{
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static void Fun(ref BigInteger a, ref BigInteger b, int c)
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{
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BigInteger t = a; a = b; b = b * c + t;
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}
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static void SolvePell(int n, ref BigInteger a, ref BigInteger b)
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{
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int x = (int)Math.Sqrt(n), y = x, z = 1, r = x << 1;
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BigInteger e1 = 1, e2 = 0, f1 = 0, f2 = 1;
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while (true)
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{
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y = r * z - y; z = (n - y * y) / z; r = (x + y) / z;
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Fun(ref e1, ref e2, r); Fun(ref f1, ref f2, r); a = f2; b = e2; Fun(ref b, ref a, x);
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if (a * a - n * b * b == 1) return;
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}
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}
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static void Main()
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{
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BigInteger x, y; foreach (int n in new[] { 61, 109, 181, 277 })
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{
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SolvePell(n, ref x, ref y);
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Console.WriteLine("x^2 - {0,3} * y^2 = 1 for x = {1,27:n0} and y = {2,25:n0}", n, x, y);
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}
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}
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}
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