| 1 | #!./perl |
| 2 | |
| 3 | # |
| 4 | # test recursive functions. |
| 5 | # |
| 6 | |
| 7 | BEGIN { |
| 8 | chdir 't' if -d 't'; |
| 9 | @INC = qw(. ../lib); |
| 10 | require "./test.pl"; |
| 11 | plan(tests => 28); |
| 12 | } |
| 13 | |
| 14 | use strict; |
| 15 | |
| 16 | sub gcd { |
| 17 | return gcd($_[0] - $_[1], $_[1]) if ($_[0] > $_[1]); |
| 18 | return gcd($_[0], $_[1] - $_[0]) if ($_[0] < $_[1]); |
| 19 | $_[0]; |
| 20 | } |
| 21 | |
| 22 | sub factorial { |
| 23 | $_[0] < 2 ? 1 : $_[0] * factorial($_[0] - 1); |
| 24 | } |
| 25 | |
| 26 | sub fibonacci { |
| 27 | $_[0] < 2 ? 1 : fibonacci($_[0] - 2) + fibonacci($_[0] - 1); |
| 28 | } |
| 29 | |
| 30 | # Highly recursive, highly aggressive. |
| 31 | # Kids, don't try this at home. |
| 32 | # |
| 33 | # For example ackermann(4,1) will take quite a long time. |
| 34 | # It will simply eat away your memory. Trust me. |
| 35 | |
| 36 | sub ackermann { |
| 37 | return $_[1] + 1 if ($_[0] == 0); |
| 38 | return ackermann($_[0] - 1, 1) if ($_[1] == 0); |
| 39 | ackermann($_[0] - 1, ackermann($_[0], $_[1] - 1)); |
| 40 | } |
| 41 | |
| 42 | # Highly recursive, highly boring. |
| 43 | |
| 44 | sub takeuchi { |
| 45 | $_[1] < $_[0] ? |
| 46 | takeuchi(takeuchi($_[0] - 1, $_[1], $_[2]), |
| 47 | takeuchi($_[1] - 1, $_[2], $_[0]), |
| 48 | takeuchi($_[2] - 1, $_[0], $_[1])) |
| 49 | : $_[2]; |
| 50 | } |
| 51 | |
| 52 | is(gcd(1147, 1271), 31, "gcd(1147, 1271) == 31"); |
| 53 | |
| 54 | is(gcd(1908, 2016), 36, "gcd(1908, 2016) == 36"); |
| 55 | |
| 56 | is(factorial(10), 3628800, "factorial(10) == 3628800"); |
| 57 | |
| 58 | is(factorial(factorial(3)), 720, "factorial(factorial(3)) == 720"); |
| 59 | |
| 60 | is(fibonacci(10), 89, "fibonacci(10) == 89"); |
| 61 | |
| 62 | is(fibonacci(fibonacci(7)), 17711, "fibonacci(fibonacci(7)) == 17711"); |
| 63 | |
| 64 | my @ack = qw(1 2 3 4 2 3 4 5 3 5 7 9 5 13 29 61); |
| 65 | |
| 66 | for my $x (0..3) { |
| 67 | for my $y (0..3) { |
| 68 | my $a = ackermann($x, $y); |
| 69 | is($a, shift(@ack), "ackermann($x, $y) == $a"); |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | my ($x, $y, $z) = (18, 12, 6); |
| 74 | |
| 75 | is(takeuchi($x, $y, $z), $z + 1, "takeuchi($x, $y, $z) == $z + 1"); |
| 76 | |
| 77 | { |
| 78 | sub get_first1 { |
| 79 | get_list1(@_)->[0]; |
| 80 | } |
| 81 | |
| 82 | sub get_list1 { |
| 83 | return [curr_test] unless $_[0]; |
| 84 | my $u = get_first1(0); |
| 85 | [$u]; |
| 86 | } |
| 87 | my $x = get_first1(1); |
| 88 | ok($x, "premature FREETMPS (change 5699)"); |
| 89 | } |
| 90 | |
| 91 | { |
| 92 | sub get_first2 { |
| 93 | return get_list2(@_)->[0]; |
| 94 | } |
| 95 | |
| 96 | sub get_list2 { |
| 97 | return [curr_test] unless $_[0]; |
| 98 | my $u = get_first2(0); |
| 99 | return [$u]; |
| 100 | } |
| 101 | my $x = get_first2(1); |
| 102 | ok($x, "premature FREETMPS (change 5699)"); |
| 103 | } |
| 104 | |
| 105 | { |
| 106 | local $^W = 0; # We do not need recursion depth warning. |
| 107 | |
| 108 | sub sillysum { |
| 109 | return $_[0] + ($_[0] > 0 ? sillysum($_[0] - 1) : 0); |
| 110 | } |
| 111 | |
| 112 | is(sillysum(1000), 1000*1001/2, "recursive sum of 1..1000"); |
| 113 | } |
| 114 | |
| 115 | # check ok for recursion depth > 65536 |
| 116 | { |
| 117 | my $r; |
| 118 | eval { |
| 119 | $r = runperl( |
| 120 | nolib => 1, |
| 121 | stderr => 1, |
| 122 | prog => q{$d=0; $e=1; sub c { ++$d; if ($d > 66000) { $e=0 } else { c(); c() unless $d % 32768 } --$d } c(); exit $e}); |
| 123 | }; |
| 124 | SKIP: { |
| 125 | skip("Out of memory -- increase your data/heap?", 2) |
| 126 | if $r =~ /Out of memory/i; |
| 127 | is($r, '', "64K deep recursion - no output expected"); |
| 128 | is($?, 0, "64K deep recursion - no coredump expected"); |
| 129 | } |
| 130 | } |
| 131 | |