Largest palindrome product: Difference between revisions
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913 * 993 = 906609 |
913 * 993 = 906609 |
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done... |
done... |
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</pre> |
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=={{header|Wren}}== |
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<lang ecmascript>var pow = 10 |
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for (n in 2..7) { |
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var low = pow * 9 + 1 |
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pow = pow * 10 |
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var high = pow - 1 |
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System.write("Largest palindromic product of two %(n)-digit integers: ") |
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var nextN = false |
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for (i in high..low) { |
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for (j in high..low) { |
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var p = i * j |
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if (p%10 != 9) continue |
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var s = p.toString |
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if (s == s[-1..0]) { |
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System.print("%(i) x %(j) = %(p)") |
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nextN = true |
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break |
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} |
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} |
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if (nextN) break |
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} |
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}</lang> |
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{{out}} |
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<pre> |
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Largest palindromic product of two 2-digit integers: 99 x 91 = 9009 |
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Largest palindromic product of two 3-digit integers: 993 x 913 = 906609 |
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Largest palindromic product of two 4-digit integers: 9999 x 9901 = 99000099 |
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Largest palindromic product of two 5-digit integers: 99979 x 99681 = 9966006699 |
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Largest palindromic product of two 6-digit integers: 999999 x 999001 = 999000000999 |
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Largest palindromic product of two 7-digit integers: 9999979 x 9467731 = 94677111177649 |
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</pre> |
</pre> |
Revision as of 10:29, 3 November 2021
Largest palindrome product is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
- Task
Task description is taken from Project Euler (https://projecteuler.net/problem=4)
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
Find the largest palindrome made from the product of two 3-digit numbers.
Raku
<lang perl6>use Prime::Factor; (^6).map: -> $oom {
LOOP: for (+(1 ~ (0 x $oom)) .. +(9 ~ (9 x $oom))).reverse.map({ +($_ ~ .flip) }) -> $pal { for my @factors = $pal.&divisors.grep: {.chars == ($oom + 1)} { next unless $pal div $_ ∈ @factors; say "Largest palindromic product of two {$oom + 1}-digit integers: $_ × {$pal div $_} = $pal" and last LOOP; } }
}</lang>
Largest palindromic product of two 2-digit integers: 91 × 99 = 9009 Largest palindromic product of two 3-digit integers: 993 × 913 = 906609 Largest palindromic product of two 4-digit integers: 9901 × 9999 = 99000099 Largest palindromic product of two 5-digit integers: 99681 × 99979 = 9966006699 Largest palindromic product of two 6-digit integers: 999999 × 999001 = 999000000999
Ring
<lang ring> load "stdlib.ring" see "working..." + nl
prodOld = 0 limitStart = 100 limitEnd = 999
for n = limitStart to limitEnd
for m = limitStart to limitEnd prodNew = n*m if prodNew > prodOld and palindrome(string(prodNew)) prodOld = prodNew first = n second = m ok next
next
see "The largest palindrome is:" + nl see "" + first + " * " + second + " = " + prodOld + nl see "done..." + nl </lang>
- Output:
working... The largest palindrome is: 913 * 993 = 906609 done...
Wren
<lang ecmascript>var pow = 10 for (n in 2..7) {
var low = pow * 9 + 1 pow = pow * 10 var high = pow - 1 System.write("Largest palindromic product of two %(n)-digit integers: ") var nextN = false for (i in high..low) { for (j in high..low) { var p = i * j if (p%10 != 9) continue var s = p.toString if (s == s[-1..0]) { System.print("%(i) x %(j) = %(p)") nextN = true break } } if (nextN) break }
}</lang>
- Output:
Largest palindromic product of two 2-digit integers: 99 x 91 = 9009 Largest palindromic product of two 3-digit integers: 993 x 913 = 906609 Largest palindromic product of two 4-digit integers: 9999 x 9901 = 99000099 Largest palindromic product of two 5-digit integers: 99979 x 99681 = 9966006699 Largest palindromic product of two 6-digit integers: 999999 x 999001 = 999000000999 Largest palindromic product of two 7-digit integers: 9999979 x 9467731 = 94677111177649