Concatenate two primes is also prime: Difference between revisions
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=={{header|Go}}== |
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{{libheader|Go-rcu}} |
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<lang go>package main |
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import ( |
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"fmt" |
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"rcu" |
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"sort" |
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) |
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func main() { |
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const LIMIT = 99 |
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primes := rcu.Primes(LIMIT) |
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rmap := make(map[int]bool) |
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for _, p := range primes { |
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for _, q := range primes { |
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var pq int |
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if q < 10 { |
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pq = p*10 + q |
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} else { |
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pq = p*100 + q |
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} |
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if rcu.IsPrime(pq) { |
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rmap[pq] = true |
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} |
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} |
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} |
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results := make([]int, len(rmap)) |
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i := 0 |
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for k := range rmap { |
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results[i] = k |
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i++ |
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} |
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sort.Ints(results) |
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fmt.Println("Two primes under 100 concatenated together to form another prime:") |
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for i, p := range results { |
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fmt.Printf("%5s ", rcu.Commatize(p)) |
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if (i+1)%10 == 0 { |
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fmt.Println() |
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} |
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} |
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fmt.Println("\n\nFound", len(results), "such concatenated primes.") |
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}</lang> |
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{{out}} |
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<pre> |
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Two primes under 100 concatenated together to form another prime: |
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23 37 53 73 113 137 173 193 197 211 |
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223 229 233 241 271 283 293 311 313 317 |
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331 337 347 353 359 367 373 379 383 389 |
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397 433 523 541 547 571 593 613 617 673 |
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677 719 733 743 761 773 797 977 1,117 1,123 |
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1,129 1,153 1,171 1,319 1,361 1,367 1,373 1,723 1,741 1,747 |
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1,753 1,759 1,783 1,789 1,913 1,931 1,973 1,979 1,997 2,311 |
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2,341 2,347 2,371 2,383 2,389 2,917 2,953 2,971 3,119 3,137 |
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3,167 3,719 3,761 3,767 3,779 3,797 4,111 4,129 4,153 4,159 |
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4,337 4,373 4,397 4,723 4,729 4,759 4,783 4,789 5,323 5,347 |
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5,923 5,953 6,113 6,131 6,143 6,173 6,197 6,719 6,737 6,761 |
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6,779 7,129 7,159 7,331 7,919 7,937 8,311 8,317 8,329 8,353 |
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8,389 8,923 8,929 8,941 8,971 9,719 9,743 9,767 |
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Found 128 such concatenated primes. |
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</pre> |
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=={{header|Perl}}== |
=={{header|Perl}}== |