Largest palindrome product: Difference between revisions
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→Stretch: changed output format
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===Stretch===
Showing results for 2 through 10 digit factors.▼
<lang csharp>using System;
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if (isPal(p)) {
if (p > bp) bp = p;
bs = string.Format(" {0,2} {1,10} x {
p -= yy; c += 10; }
y -= ld == 7 ? 44 : 22; }
Line 229 ⟶ 228:
static void Main(string[] args) {
Console.WriteLine("digs factor factor palindrome");
var sw = System.Diagnostics.Stopwatch.StartNew();
for (int i = 2, h = 1; i <= 10; h = ++i >> 1) {
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a = new string('9', h) + new string('0', (h) - 1) + "1",
c = new string('9', h) + new string('0', i) + new string('9', h);
Console.WriteLine(" {0,2} {1,10} x {
else doOne(i);
}
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}</lang>
{{out|Output @ Tio.run}}
▲Showing results for 2 through 10 digit factors.
<pre>digs factor factor palindrome
913 x 993 = 906609▼
2 91 x 99 = 9009
9901 x 9999 = 99000099▼
▲ 3 913 x 993 = 906609
99979 x 99681 = 9966006699▼
▲ 4 9901 x 9999 = 99000099
999001 x 999999 = 999000000999▼
▲ 5 99979 x 99681 = 9966006699
9997647 x 9998017 = 99956644665999▼
▲ 6 999001 x 999999 = 999000000999
99990001 x 99999999 = 9999000000009999▼
▲ 7 9997647 x 9998017 = 99956644665999
999920317 x 999980347 = 999900665566009999▼
▲ 8 99990001 x 99999999 = 9999000000009999
9999900001 x 9999999999 = 99999000000000099999▼
▲ 9 999920317 x 999980347 = 999900665566009999
2.2502339 sec</pre>Wow! how did that go so fast? The results for the even-number-of-digit factors were manufactured by string manipulation instead of calculation (since the pattern was obvious). This algorithm can easily be adapted to BigIntegers for higher n-digit factors, but the execution time is unspectacular.▼
▲ 10 9999900001 x 9999999999 = 99999000000000099999
▲2.
=={{header|F_Sharp|F#}}==
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