blob: 00ffe0c25a815271de958750a9d7ece96cb9b272 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
#!/usr/bin/env perl
use strict;
use warnings;
use feature qw{ say signatures state };
no warnings qw{ experimental };
use Getopt::Long;
my $n = 1;
GetOptions( 'number=i' => \$n, );
my $start;
for my $i ( 1 .. 5 ) {
if ( !defined $start ) {
$start = Node->new($i);
}
else {
my $last = get_last($start);
$last->next( Node->new($i) );
}
}
trim_list( $start, $n );
sub trim_list ( $link, $n = 1 ) {
# how big is the linked list?
my $i = 0;
my $s = $link;
while ( defined $s ) {
$i++;
$s = $s->{next};
}
my $stop = $i - $n + 1;
$stop = $stop < 1 ? 1 : $stop;
$i = 1;
$s = $link;
while ( defined $s ) {
$s->remove if $i == $stop;
$s = $s->{next};
$i++;
}
show_list($start);
}
sub show_list( $link ) {
while ( defined $link ) {
print $link->{value} || '';
if ( defined $link->{next} ) {
print ' -> '
if defined $link->{next};
}
else { print "\n" if !defined $link->{next}; }
$link = $link->{next};
}
}
sub get_last( $node ) {
return get_last( $node->next ) if $node->next;
return $node;
}
# copied and pasted from my Challenge #59 code
######### ######### ######### ######### ######### ######### #########
# The same old Node code, but instead of left and right,
# it just has next
package Node;
sub new ( $class, $value = 0 ) {
my $self = {};
$self->{value} = $value;
$self->{next} = undef;
$self->{parent} = undef;
return bless $self, $class;
}
sub value ( $self ) {
return $self->{value};
}
sub is_root ( $self ) {
return defined $self->{parent} ? 0 : 1;
}
sub is_leaf ( $self ) {
return ( !defined $self->{left} && !defined $self->{right} )
? 1
: 0;
}
sub next ( $self, $node = undef ) {
if ( defined $node ) {
$self->{next} = $node;
$node->{parent} = $self;
}
else {
return $self->{next};
}
}
sub parent ($self ) {
return $self->{parent};
}
# this one is added.
# because we cannot replace self, we must redefine
# $self and remove next when trying to remove first
# element
sub remove ( $self ) {
my $parent = $self->{parent};
my $next = $self->{next};
if ( defined $parent && defined $next ) {
$parent->{next} = $next;
$next->{parent} = $parent;
}
elsif ( defined $parent ) {
$parent->{next} = undef;
}
elsif ( defined $next ) {
$self->{value} = $next->{value};
$next->remove;
}
}
|
