Practical numbers: Difference between revisions
Added XPL0 example.
Drkameleon (talk | contribs) (added Arturo) |
(Added XPL0 example.) |
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666 is practical: true
</pre>
=={{header|XPL0}}==
<syntaxhighlight lang "XPL0">int Divs(32), NumDivs;
proc GetDivs(N); \Fill array Divs with proper divisors of N
int N, I, Div, Quot;
[Divs(0):= 1; I:= 1; Div:= 2;
loop [Quot:= N/Div;
if Div > Quot then quit;
if rem(0) = 0 then
[Divs(I):= Div; I:= I+1;
if Div # Quot then
[Divs(I):= Quot; I:= I+1];
if I > 30 then
[Text(0, "beyond the limit of 30 divisors.^m^j"); exit];
];
Div:= Div+1;
];
NumDivs:= I;
];
func PowerSet(N); \Return 'true' if some combination of Divs sums to N
int N, I, J, Sum;
[for I:= 0 to 1<<NumDivs - 1 do \(beware of 1<<31 - 1 infinite loop)
[Sum:= 0;
for J:= 0 to NumDivs-1 do
[if I & 1<<J then \for all set bits...
[Sum:= Sum + Divs(J);
if Sum = N then return true;
];
];
];
return false;
];
func Practical(X); \Return 'true' if X is a practical number
int X, N;
[GetDivs(X);
for N:= 1 to X-1 do
if PowerSet(N) = false then return false;
return true;
];
int N, I;
[for N:= 1 to 333 do
if Practical(N) then
[IntOut(0, N); ChOut(0, ^ )];
CrLf(0);
N:= [666, 6666, 66666, 672, 720, 222222];
for I:= 0 to 6-1 do
[IntOut(0, N(I)); Text(0, " is ");
if not Practical(N(I)) then Text(0, "not ");
Text(0, "a practical number.^m^j");
];
]</syntaxhighlight>
{{out}}
<pre>
1 2 4 6 8 12 16 18 20 24 28 30 32 36 40 42 48 54 56 60 64 66 72 78 80 84 88 90 96 100 104 108 112 120 126 128 132 140 144 150 156 160 162 168 176 180 192 196 198 200 204 208 210 216 220 224 228 234 240 252 256 260 264 270 272 276 280 288 294 300 304 306 308 312 320 324 330
666 is a practical number.
6666 is a practical number.
66666 is not a practical number.
672 is a practical number.
720 is a practical number.
222222 is beyond the limit of 30 divisors.
</pre>
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