Own digits power sum: Difference between revisions

=={{header|Java}}==

<syntaxhighlight lang="java">

import java.util.List;

import java.util.stream.Collectors;

import java.util.stream.IntStream;

public final class OwnDigitsPowerSum {

public static void main(String[] args) {

List<Integer> powers = IntStream.rangeClosed(0, 9).boxed().map( i -> i * i ).collect(Collectors.toList());

System.out.println("Own digits power sums for N = 3 to 9 inclusive:");

for ( int n = 3; n <= 9; n++ ) {

for ( int d = 2; d <= 9; d++ ) {

powers.set(d, powers.get(d) * d);

}

long i = (long) Math.pow(10, n - 1);

long max = i * 10;

int lastDigit = 0;

int sum = 0;

List<Integer> digits;

while ( i < max ) {

if ( lastDigit == 0 ) {

digits = String.valueOf(i).chars().map(Character::getNumericValue).boxed().toList();

sum = digits.stream().map( d -> powers.get(d) ).mapToInt(Integer::intValue).sum();

} else if ( lastDigit == 1 ) {

sum += 1;

} else {

sum += powers.get(lastDigit) - powers.get(lastDigit - 1);

}

if ( sum == i ) {

System.out.println(i);

if ( lastDigit == 0 ) {

System.out.println(i + 1);

}

i += 10 - lastDigit;

lastDigit = 0;

} else if ( sum > i ) {

i += 10 - lastDigit;

lastDigit = 0;

} else if ( lastDigit < 9 ) {

i += 1;

lastDigit += 1;

} else {

i += 1;

lastDigit = 0;

}

}

}

}

}

</syntaxhighlight>

{{ out }}

<pre>

Own digits power sums for N = 3 to 9 inclusive:

153

370

371

407

1634

8208

9474

54748

92727

93084

548834

1741725

4210818

9800817

9926315

24678050

24678051

88593477

146511208

472335975

534494836

912985153

</pre>