First power of 2 that has leading decimal digits of 12: Difference between revisions
First power of 2 that has leading decimal digits of 12 (view source)
Revision as of 03:05, 12 September 2020
, 3 years ago→{{header|Factor}}
Line 391:
p( 99, 1) = 93
Took 00:00:00.1391226 seconds</pre>
=={{header|D}}==
{{trans|C}}
<lang d>import std.math;
import std.stdio;
int p(int l, int n) {
int test = 0;
double logv = log(2.0) / log(10.0);
int factor = 1;
int loop = l;
while (loop > 10) {
factor *= 10;
loop /= 10;
}
while (n > 0) {
int val;
test++;
val = cast(int)(factor * pow(10.0, fmod(test * logv, 1)));
if (val == l) {
n--;
}
}
return test;
}
void runTest(int l, int n) {
writefln("p(%d, %d) = %d", l, n, p(l, n));
}
void main() {
runTest(12, 1);
runTest(12, 2);
runTest(123, 45);
runTest(123, 12345);
runTest(123, 678910);
}</lang>
{{out}}
<pre>p(12, 1) = 7
p(12, 2) = 80
p(123, 45) = 12710
p(123, 12345) = 3510491
p(123, 678910) = 193060223</pre>
=={{header|Factor}}==
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