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Descending primes: Difference between revisions

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Descending primes (view source)

Revision as of 05:59, 3 August 2022

372 bytes added ,  1 year ago
→‎{{header|Ring}}: Rewrote code, removed warning
(→‎{{header|Ring}}: Rewrote code, removed warning)
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=={{header|Ring}}==
<lang ring>show("decending primes", sort(cending_primes(seq(9, 1))))
{{incorrect|Ring| <br> Many of the numbers shown do not have strictly descending digits, e.g. all the ones starting with 2 (except 2 itself). <br> Largest is much larger than 1000. }}
<lang ring>
load "stdlibcore.ring"
 
func show(title, itm)
limit = 1000
l = len(itm); ? "" + l + " " + title + ":"
row = 0
for ni = 1 to limitl▼
see fmt(itm[i], 9)
if i % 5 = 0 and i < l? flag ="" 1ok▼
next : ? ""
 
func seq(b, e)
▲for n = 1 to limit
res = flag[]; d = 0e - b
s = strnd =/ stringfabs(nd)
for i = b to e step s add(res, i) next
if isprime(n) = 1
return res
for m = 1 to len(strn)-1
 
if number(substr(strn,m)) < number(substr(strn,m+1))
func ispr(n)
▲ flag = 1
if n < 2 return 0 ok
if n & 1 = next0 return n = 2 ok
if n % 3 = if0 flagreturn n = 13 ok
l = row++sqrt(n)
for f = 5 to see "" + n + " "l
if n % f = 0 or n % (f + 2) = 0 return false ok
ok▼
next : return 1
if row % 10 = 0
 
see nl
func cending_primes(digs)
ok
cand = ok[0]
pr = []
next▼
for i in digs
</lang>
lcand = cand
Output:
for j in lcand
<br>
2 3 5 7 11 13 17v 19= 23j 29* 10 + i
31 37 41 43 47 53 59if 61ispr(v) 67add(pr, 71v) ok
add(cand, v)
73 79 83 89 97 101 103 107 109 113
▲ oknext
127 131 137 139 149 151 157 163 167 173
▲ next
179 181 191 193 197 199 211 223 227 229
return pr
233 239 241 251 257 263 269 271 277 281
 
283 293 307 311 313 317 331 337 347 349
func fmt(x, l)
353 359 367 373 379 383 389 397 401 409
419 421 431res 433= 439" 443 449 457 461 463 " + x
return right(res, l)</lang>
467 479 487 491 499 503 509 521 523 541
{{out}}
547 557 563 569 571 577 587 593 599 601
<pre>87 decending primes:
607 613 617 619 631 641 643 647 653 659
2 3 5 7 31
661 673 677 683 691 701 709 719 727 733
41 43 53 61 71
739 743 751 757 761 769 773 787 797 809
73 83 97 421 431
811 821 823 827 829 839 853 857 859 863
521 541 631 641 643
877 881 883 887 907 911 919 929 937 941
653 743 751 761 821
947 953 967 971 977 983 991 997
853 863 941 953 971
983 5431 6421 6521 7321
7541 7621 7643 8431 8521
8543 8641 8731 8741 8753
8761 9421 9431 9521 9631
9643 9721 9743 9851 9871
75431 76421 76541 76543 86531
87421 87541 87631 87641 87643
94321 96431 97651 98321 98543
98621 98641 98731 764321 865321
876431 975421 986543 987541 987631
8764321 8765321 9754321 9875321 97654321
98764321 98765431</pre>
 
=={{header|Ruby}}==
Retrieved from "https://rosettacode.org/wiki/Special:MobileDiff/320384"