Return to test.pl CVS log

Up to [LON-CAPA] / loncom / homework / caparesponse

- BUG#33
   - multiple correct answer can be defined
   - when there are multiple values defined, you can set it to accept them in any order

    1: use strict;
    2: use warnings;
    3: 
    4: my $n = 0;
    5: my $total = 0;
    6: my $num_left = 0;
    7: my @order;
    8: 
    9: sub factorial {
   10:     my $input = CORE::int(shift);
   11:     return "Error - unable to take factorial of an negative number ($input)" if $input < 0;
   12:     return "Error - factorial result is greater than system limit ($input)" if $input > 170;
   13:     return 1 if $input == 0;
   14:     my $result = 1; 
   15:     for (my $i=2; $i<=$input; $i++) { $result *= $i }
   16:     return $result;
   17: }
   18: 
   19: sub init {
   20:     my ($size) = @_;
   21:     @order = (0..$size-1);
   22:     $n = $size;
   23:     $total = $num_left = &factorial($size);
   24: }
   25: 
   26: sub get_next {
   27:     if ($num_left == $total) {
   28: 	$num_left--;
   29: 	return @order;
   30:     }
   31: 
   32: 
   33:     # Find largest index j with a[j] < a[j+1]
   34: 
   35:     my $j = scalar(@order) - 2;
   36:     while ($order[$j] > $order[$j+1]) {
   37: 	$j--;
   38:     }
   39: 
   40:     # Find index k such that a[k] is smallest integer
   41:     # greater than a[j] to the right of a[j]
   42: 
   43:     my $k = scalar(@order) - 1;
   44:     while ($order[$j] > $order[$k]) {
   45: 	$k--;
   46:     }
   47: 
   48:     # Interchange a[j] and a[k]
   49: 
   50:     @order[($k,$j)] = @order[($j,$k)];
   51: 
   52:     # Put tail end of permutation after jth position in increasing order
   53: 
   54:     my $r = scalar(@order) - 1;
   55:     my $s = $j + 1;
   56: 
   57:     while ($r > $s) {
   58: 	@order[($s,$r)]=@order[($r,$s)];
   59: 	$r--;
   60: 	$s++;
   61:     }
   62: 
   63:     $num_left--;
   64:     return(@order);
   65: }
   66: 
   67: &init(9);
   68: while($num_left) {
   69:     print(join(':',&get_next()).$/);
   70: }