Amicable pairs: Difference between revisions
→{{header|Lua}}: Replaced time with time from TIO.RUN, added alternative version that doesn't use division/modulo
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(→{{header|Lua}}: Replaced time with time from TIO.RUN, added alternative version that doesn't use division/modulo) |
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Line 3,486:
=={{header|Lua}}==
Avoids unnecessary divisor sum calculations.<br>
Runs in around 0.11 seconds on TIO.RUN.
<syntaxhighlight lang="lua">function sumDivs (n)
local sum = 1
Line 3,507 ⟶ 3,508:
{{out}}<pre>
220 284
1184 1210
2620 2924
5020 5564
6232 6368
10744 10856
12285 14595
17296 18416
</pre>
Alternative version using a table of proper divisors, constructed without division/modulo.<br>
Runs is around 0.02 seconds on TIO.RUN.
<syntaxhighlight lang="lua">
MAX_NUMBER = 20000
sumDivs = {} -- table of proper divisors
for i = 1, MAX_NUMBER do sumDivs[ i ] = 1 end
for i = 2, MAX_NUMBER do
for j = i + i, MAX_NUMBER, i do
sumDivs[ j ] = sumDivs[ j ] + i
end
end
for n = 2, MAX_NUMBER do
m = sumDivs[n]
if m > n then
if sumDivs[m] == n then print(n, m) end
end
end
</syntaxhighlight>
{{out}}
<pre>
220 284
1184 1210
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