Successive prime differences: Difference between revisions
→{{header|C sharp}}: filled in missing GeneratePrimes() function
(→{{header|C sharp}}: filled in missing GeneratePrimes() function) |
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using static System.Linq.Enumerable;
public static class SuccessivePrimeDifferences {
public static void Main() {
var primes = GeneratePrimes(1_000_000).ToList();
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IEnumerable<IEnumerable<int>> FindDifferenceGroups(int[] diffs) {
for (int pi = diffs.Length; pi < primes.Count; pi++)
if (Range(0, diffs.Length).All(di => primes[pi-diffs.Length+di+1] - primes[pi-diffs.Length+di] == diffs[di]))
yield return Range(pi - diffs.Length, diffs.Length + 1).Select(i => primes[i]);
IEnumerable<int> GeneratePrimes(int lmt) {
bool[] comps = new bool[lmt + 1];
comps[0] = comps[1] = true;
yield return 2; yield return 3;
for (int j = 4; j <= lmt; j += 2) comps[j] = true;
for (int j = 9; j <= lmt; j += 6) comps[j] = true;
int i = 5, d = 4, rt = (int)Math.Sqrt(lmt);
for ( ; i <= rt; i += (d = 6 - d))
if (!comps[i]) {
yield return i;
for (int j = i * i, k = i << 1; j <= lmt; j += k)
comps[j] = true;
}
for ( ; i <= lmt; i += (d = 6 - d)) if (!comps[i]) yield return i;
▲ }
}
}
}</lang>
{{out}}
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