--- loncom/homework/caparesponse/test.pl	2005/01/31 21:53:51	1.2
+++ loncom/homework/caparesponse/test.pl	2006/09/29 20:55:36	1.3
@@ -1,14 +1,70 @@
 use strict;
-use capa;
+use warnings;
 
-my $unit="N";
-my $answer="3.4 N";
-my $scaled="3.2";
-print("\n return code is (should be 6)".&capa::caparesponse_get_real_response($unit,$answer,\$scaled));
-print("\nscaled (should be 0.0034) ".$scaled." unit $unit answer $answer");
-$unit="m";
-$answer="3.4 mm/J";
-$scaled=3.2;
-print("\n return code is (should be 15)".&capa::caparesponse_get_real_response($unit,$answer,\$scaled));
-print("\nscaled (should be 3.2) ".$scaled." unit $unit answer $answer");
-print("\n");
+my $n = 0;
+my $total = 0;
+my $num_left = 0;
+my @order;
+
+sub factorial {
+    my $input = CORE::int(shift);
+    return "Error - unable to take factorial of an negative number ($input)" if $input < 0;
+    return "Error - factorial result is greater than system limit ($input)" if $input > 170;
+    return 1 if $input == 0;
+    my $result = 1; 
+    for (my $i=2; $i<=$input; $i++) { $result *= $i }
+    return $result;
+}
+
+sub init {
+    my ($size) = @_;
+    @order = (0..$size-1);
+    $n = $size;
+    $total = $num_left = &factorial($size);
+}
+
+sub get_next {
+    if ($num_left == $total) {
+	$num_left--;
+	return @order;
+    }
+
+
+    # Find largest index j with a[j] < a[j+1]
+
+    my $j = scalar(@order) - 2;
+    while ($order[$j] > $order[$j+1]) {
+	$j--;
+    }
+
+    # Find index k such that a[k] is smallest integer
+    # greater than a[j] to the right of a[j]
+
+    my $k = scalar(@order) - 1;
+    while ($order[$j] > $order[$k]) {
+	$k--;
+    }
+
+    # Interchange a[j] and a[k]
+
+    @order[($k,$j)] = @order[($j,$k)];
+
+    # Put tail end of permutation after jth position in increasing order
+
+    my $r = scalar(@order) - 1;
+    my $s = $j + 1;
+
+    while ($r > $s) {
+	@order[($s,$r)]=@order[($r,$s)];
+	$r--;
+	$s++;
+    }
+
+    $num_left--;
+    return(@order);
+}
+
+&init(9);
+while($num_left) {
+    print(join(':',&get_next()).$/);
+}