# binary-trees Perl program

## source code

```# The Computer Language Benchmarks Game
# https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
#
# contributed by Emanuele Zeppieri
# *reset* by A. Sinan Unur

run( @ARGV );

sub bottomup_tree {
my \$depth = shift;
return 0 unless \$depth;
--\$depth;
[ bottomup_tree(\$depth), bottomup_tree(\$depth) ];
}

sub check_tree {
return 1 unless ref \$_[0];
1 + check_tree(\$_[0][0]) + check_tree(\$_[0][1]);
}

sub stretch_tree {
my \$stretch_depth = shift;
my \$stretch_tree = bottomup_tree(\$stretch_depth);
print "stretch tree of depth \$stretch_depth\t check: ",
check_tree(\$stretch_tree), "\n";
}

sub run {
my \$max_depth = shift;
my \$min_depth = 4;

\$max_depth = \$min_depth + 2 if \$min_depth + 2 > \$max_depth;

stretch_tree( \$max_depth + 1 );

my \$longlived_tree = bottomup_tree(\$max_depth);

for ( my \$depth = \$min_depth; \$depth <= \$max_depth; \$depth += 2 ) {
my \$iterations = 2**(\$max_depth - \$depth + \$min_depth);
my \$check = 0;

foreach (1..\$iterations) {
\$check += check_tree( bottomup_tree(\$depth) );
}

print \$iterations, "\t trees of depth \$depth\t check: ", \$check, "\n"
}

print "long lived tree of depth \$max_depth\t check: ",
check_tree(\$longlived_tree), "\n"
}

```

## notes, command-line, and program output

```NOTES:
This is perl 5, version 40
subversion 0 (v5.40.0)

Mon, 10 Jun 2024 17:41:15 GMT

COMMAND LINE:
/opt/src/perl-5.40.0/bin/perl binarytrees.perl 21

PROGRAM OUTPUT:
stretch tree of depth 22	 check: 8388607
2097152	 trees of depth 4	 check: 65011712
524288	 trees of depth 6	 check: 66584576
131072	 trees of depth 8	 check: 66977792
32768	 trees of depth 10	 check: 67076096
8192	 trees of depth 12	 check: 67100672
2048	 trees of depth 14	 check: 67106816
512	 trees of depth 16	 check: 67108352
128	 trees of depth 18	 check: 67108736
32	 trees of depth 20	 check: 67108832
long lived tree of depth 21	 check: 4194303
```