Partition an integer x into n primes: Difference between revisions
Partition an integer x into n primes (view source)
Revision as of 08:31, 10 April 2024
, 1 month agoAdd BCPL
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Partition 22699 with 4 primes: 2+3+43+22651
Partition 40355 with 3 primes: 3+139+40213</pre>
=={{header|BCPL}}==
<syntaxhighlight lang="bcpl">get "libhdr"
let sieve(n, prime) be
$( let i = 2
0!prime := false
1!prime := false
for i = 2 to n do i!prime := true
while i*i <= n
$( let j = i*i
while j <= n
$( j!prime := false
j := j+i
$)
i := i+1
$)
$)
let partition(x, n, prime, p, part) =
p > x -> false,
n = 1 -> valof $( !part := x; resultis x!prime $),
valof
$( p := p+1 repeatuntil p!prime
!part := p
if partition(x-p, n-1, prime, p, part+1) resultis true
resultis partition(x, n, prime, p, part)
$)
let showpart(n, part) be
$( writef("%N", !part)
unless n=1 do
$( wrch('+')
showpart(n-1, part+1)
$)
$)
let show(x, n, prime) be
$( let part = vec 32
writef("Partitioned %N with %N prime%S: ", x, n, n=1->"", "s")
test partition(x, n, prime, 1, part)
do showpart(n, part)
or writes("not possible")
newline()
$)
let start() be
$( let prime = getvec(100000)
let tests = table 99809,1, 18,2, 19,3, 20,4, 2017,24,
22699,1, 22699,2, 22699,3, 22699,4, 40355,3
sieve(100000, prime)
for t = 0 to 9 do show(tests!(t*2), tests!(t*2+1), prime)
freevec(prime)
$)</syntaxhighlight>
{{out}}
<pre>Partitioned 99809 with 1 prime: 99809
Partitioned 18 with 2 primes: 5+13
Partitioned 19 with 3 primes: 3+5+11
Partitioned 20 with 4 primes: not possible
Partitioned 2017 with 24 primes: 2+3+5+7+11+13+17+19+23+29+31+37+41+43+47+53+59+61+67+71+73+79+97+1129
Partitioned 22699 with 1 prime: 22699
Partitioned 22699 with 2 primes: 2+22697
Partitioned 22699 with 3 primes: 3+5+22691
Partitioned 22699 with 4 primes: 2+3+43+22651
Partitioned 40355 with 3 primes: 3+139+40213</pre>
=={{header|C}}==
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