Re: Randomly select values from array

[BrowserUk]

selecting for of them ... no numbers left in the array

Assuming that "for of them" means "four of them", then you have an immediate problem in that if your array contains 50 (or 51, or 53, or 54 or 55 etc. ) values, then you will eventually reach a point where there are less than four left to pick. What then?

The ultimate purpose is to find all sort of combinations,

Do you mean "all possible combinations"? If so, Do you mean "all possible sets of 4 that sum to 15" or "all possible sets of sets of 4 that sum to 15"?

What if the array of numbers doesn't contain any set of four that sums to 15?

Some code for you to play with. It generates an array of 50 small numbers (0..9) and then attempts to empty the array by picking and removing sets of 4. It will never terminate (use ^C), but might illustrate some ways of approaching whichever clarification of your problem is the correct one:)

#! perl -slw
use strict;
use List::Util qw[ shuffle sum ];

my @nums = map int rand 10, 1 .. 50;
my $n = 0;
{
    my @pick = (shuffle 0 .. $#nums )[ 0 .. 3 ];
    if( 15 == sum @nums[ @pick ] ) {
        print "\n@nums[ @pick ]";
        splice @nums, $_, 1 for sort{ $b <=> $a } @pick;
        $n = 0;
    }
    printf "\rtrying to find another from [@nums]: %d", ++$n;
    redo if @nums > 4;
}

__END__
c:\test>840204.pl
trying to find another from [5 3 5 0 1 8 3 6 1 5 7 5 3 1 6 4 5 9 5 0 1
+ 6 1 3 5 0 9 1 7 8 0 7 4 9 7 5 6 0 2 3 7 9 6 1 7 7 2 0 4 9]: 3
3 8 4 0
trying to find another from [5 3 5 0 1 8 3 6 1 5 7 5 1 6 5 9 5 0 1 6 1
+ 3 5 0 9 1 7 0 7 4 9 7 5 6 0 2 3 7 9 6 1 7 7 2 4 9]: 16
5 6 3 1
trying to find another from [5 3 0 1 8 3 6 1 5 7 5 1 5 9 5 0 1 6 1 3 5
+ 0 9 7 0 7 4 9 7 5 6 0 2 7 9 6 1 7 7 2 4 9]: 24
7 0 7 1
trying to find another from [5 3 0 8 3 6 1 5 5 1 5 9 5 0 1 6 1 3 5 0 9
+ 7 7 4 9 7 5 6 0 2 7 9 6 1 7 2 4 9]: 45
0 5 4 6
trying to find another from [3 0 8 3 6 1 5 5 1 5 9 5 0 1 6 1 3 5 0 9 7
+ 7 4 9 7 5 6 2 7 9 1 7 2 9]: 9
0 3 7 5
trying to find another from [3 0 8 3 6 1 5 1 5 9 5 1 6 1 5 0 9 7 7 4 9
+ 7 5 6 2 7 9 1 2 9]: 1
7 2 1 5
trying to find another from [3 0 8 3 6 1 5 1 9 5 1 6 5 0 9 7 7 4 9 7 5
+ 6 2 9 1 9]: 41
1 3 6 5
trying to find another from [3 0 8 6 1 9 5 1 5 0 9 7 7 4 9 7 5 6 2 9 1
+ 9]: 5
7 0 7 1
trying to find another from [3 8 6 1 9 5 5 0 9 4 9 7 5 6 2 9 1 9]: 3
8 0 6 1
trying to find another from [3 6 9 5 5 9 4 9 7 5 2 9 1 9]: 86
5 2 1 7
trying to find another from [3 6 9 5 9 4 9 5 9 9]: 85635
^C

c:\test>840204.pl
trying to find another from [3 9 9 7 4 8 5 7 0 1 4 7 8 0 8 7 5 2 3 4 1
+ 6 6 3 2 5 7 5 8 5 4 4 3 5 4 6 6 6 5 3 5 3 4 0 3 4 5 1 7 4]: 10
4 0 3 8
trying to find another from [3 9 9 7 4 8 5 7 0 1 4 7 8 0 8 7 5 2 3 4 1
+ 6 6 3 2 5 7 5 5 4 3 5 4 6 6 6 5 5 3 4 3 4 5 1 7 4]: 1
4 4 1 6
trying to find another from [3 9 9 7 4 8 5 7 0 1 4 7 8 0 8 7 5 2 3 1 6
+ 6 3 2 5 7 5 5 4 3 5 4 6 6 5 5 3 4 3 5 7 4]: 7
5 5 5 0
trying to find another from [3 9 9 7 4 8 7 1 4 7 8 0 8 7 2 3 1 6 6 3 2
+ 5 7 5 5 4 3 5 4 6 6 5 3 4 3 5 7 4]: 2
3 5 3 4
trying to find another from [9 9 7 4 8 7 1 7 8 0 8 7 2 1 6 6 3 2 5 7 5
+ 5 4 3 4 6 6 5 3 4 3 5 7 4]: 10
1 2 4 8
trying to find another from [9 9 7 4 8 7 1 7 8 0 7 6 6 3 2 5 7 5 5 4 3
+ 6 6 5 3 4 3 5 7 4]: 6
3 5 4 3
trying to find another from [9 9 7 4 8 7 1 7 8 0 7 6 6 2 7 5 5 4 3 6 6
+ 5 3 5 7 4]: 22
5 0 6 4
trying to find another from [9 9 7 4 8 7 1 7 8 7 6 2 7 5 5 4 3 6 6 5 3
+ 7]: 31
7 4 3 1
trying to find another from [9 9 7 4 8 7 8 7 6 2 7 5 5 6 6 5 3 7]: 138
5 2 3 5
trying to find another from [9 9 7 4 8 7 8 7 6 7 6 6 5 7]: 74781
^C