Largest int from concatenated ints: Difference between revisions

=={{header|C++}}==

<lang cpp>#include <iostream>

#include <sstream>

#include <algorithm>

#include <vector>

#include <string>

std::string findLargestConcat ( std::vector< int > & mynumbers ) {

std::vector<std::string> concatnumbers ;

std::sort ( mynumbers.begin( ) , mynumbers.end( ) ) ;

do {

std::ostringstream numberstream ;

for ( int i : mynumbers )

numberstream << i ;

concatnumbers.push_back( numberstream.str( ) ) ;

} while ( std::next_permutation( mynumbers.begin( ) ,

mynumbers.end( ) )) ;

return *( std::max_element( concatnumbers.begin( ) ,

concatnumbers.end( ) ) ) ;

}

int main( ) {

std::vector<int> mynumbers = { 98, 76 , 45 , 34, 9 , 4 , 3 , 1 } ;

std::vector<int> othernumbers = { 54 , 546 , 548 , 60 } ;

std::cout << "The largest concatenated int is " <<

findLargestConcat( mynumbers ) << " !\n" ;

std::cout << "And here it is " << findLargestConcat( othernumbers )

<< " !\n" ;

return 0 ;

}</lang>

{{out}}

<pre>The largest concatenated int is 998764543431 !

And here it is 6054854654 !</pre>

</pre> =={{header|Go}}==

=={{header|PARI/GP}}==

Sorts then joins. Most of the noise comes from converting a vector of integers into a concatenated integer: <code>eval(concat(apply(n->Str(n),v)))</code>. Note that the short form <code>eval(concat(apply(Str,v)))</code> is not valid here because <code>Str</code> is variadic.

<lang parigp>large(v)=eval(concat(apply(n->Str(n),vecsort(v,(x,y)->eval(Str(y,x,"-",x,y))))));

large([1, 34, 3, 98, 9, 76, 45, 4])

large([54, 546, 548, 60])</lang>

{{out}}

<pre>%1 = 998764543431

%2 = 6054854654</pre>

=={{header|Raku}}==

(formerly Perl 6)

<lang perl6>sub maxnum(*@x) {

[~] @x.sort: -> $a, $b { $b ~ $a leg $a ~ $b }

}

say maxnum <1 34 3 98 9 76 45 4>;

say maxnum <54 546 548 60>;</lang>

{{out}}

<pre>998764543431

6054854654</pre>