Proper divisors: Difference between revisions

</pre>

=={{header|Action!}}==

Calculations on a real Atari 8-bit computer take quite long time. It is recommended to use an emulator capable with increasing speed of Atari CPU.

<lang Action!>BYTE FUNC CountDivisors(INT a)

INT i

BYTE prod,count

prod=1 count=0

WHILE a MOD 2=0

DO

count==+1

a==/2

OD

prod==*(1+count)

i=3

WHILE i*i<=a

DO

count=0

WHILE a MOD i=0

DO

count==+1

a==/i

OD

prod==*(1+count)

i==+2

OD

IF a>2 THEN

prod==*2

FI

RETURN (prod-1)

BYTE FUNC GetDivisors(INT a INT ARRAY divisors)

INT i,max

BYTE count

max=a/2

count=0

FOR i=1 TO max

DO

IF a MOD i=0 THEN

divisors(count)=i

count==+1

FI

OD

RETURN (count)

PROC Main()

INT i,j,count,max,ind,st,range

INT ARRAY divisors(100)

BYTE perc

FOR i=1 TO 10

DO

count=GetDivisors(i,divisors)

PrintF("%I has %I proper divisors: [",i,count)

FOR j=0 TO count-1

DO

PrintI(divisors(j))

IF j<count-1 THEN

Put(32)

FI

OD

PrintE("]")

OD

PutE() PrintE("Searching for max number of divisors:")

range=20000

max=0 ind=0 perc=0 st=range/100

FOR i=1 TO range

DO

IF i MOD st=0 THEN

PrintB(perc) Put('%) PutE() Put(28)

perc==+1

FI

count=CountDivisors(i)

IF count>max THEN

max=count ind=i

FI

OD

PrintF("%I has %I proper divisors%E",ind,max)

RETURN</lang>

{{out}}

[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Proper_divisors.png Screenshot from Atari 8-bit computer]

<pre>

1 has 0 proper divisors: []

2 has 1 proper divisors: [1]

3 has 1 proper divisors: [1]

4 has 2 proper divisors: [1 2]

5 has 1 proper divisors: [1]

6 has 3 proper divisors: [1 2 3]

7 has 1 proper divisors: [1]

8 has 3 proper divisors: [1 2 4]

9 has 2 proper divisors: [1 3]

10 has 3 proper divisors: [1 2 5]

Searching for max number of divisors:

15120 has 79 proper divisors