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April 19, 2020 22:42
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Perl Weekly Challenge 056
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use strict; | |
use warnings; | |
## | |
# You are given an array @N of positive | |
# integers (sorted) and another non negative integer k. | |
# Write a script to find if there exists two indices | |
# i and j such that A[i] - A[j] = k and i != j. | |
# Print the pairs of indices, if any such pairs exist. | |
my @N = (2, 7, 9); | |
my $k = 2; | |
my @pairs; | |
for my $i (0 .. @N - 1){ | |
for my $j (0 .. @N - 1){ | |
push @pairs, [$i, $j] if($N[$i] - $N[$j] == $k && $i != $j); | |
} | |
} | |
if(!@pairs){ | |
print "No matching pairs\n"; | |
} | |
elsif(@pairs == 1){ | |
print "Matching Pair: "; | |
print "(" . join(",", @{$pairs[0]}) . ")\n"; | |
} | |
else{ | |
print "Matching Pairs: "; | |
for my $i (0 .. @pairs - 2){ | |
print "(" . join(",", @{$pairs[$i]}) . "), "; | |
} | |
print "(" . join(",", @{$pairs[@pairs - 1]}) . ")\n"; | |
} |
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use strict; | |
use warnings; | |
## | |
# You are given a binary tree and a sum, write | |
# a script to find if the tree has a path such | |
# that adding up all the values along the path | |
# Only complete paths (from root to leaf node) | |
# may be considered for a sum. | |
## | |
use Graph; | |
use boolean; | |
use Graph::Easy::Parser; | |
use constant SUM => 35; | |
sub insert{ | |
my($graph, $root, $next) = @_; | |
if(!$graph->vertices()){ | |
$graph->add_vertex($next); | |
$graph->set_edge_attribute($next, "left", "left", true); | |
$graph->set_edge_attribute($next, "right", "right", true); | |
return $next; | |
} | |
if($root > $next){ | |
if($graph->has_edge_attribute($root, "left", "left")){ | |
$graph->delete_edge_attributes($root, "left"); | |
$graph->set_edge_attribute($root, $next, "left", true); | |
$graph->set_edge_attribute($next, "left", "left", true); | |
$graph->set_edge_attribute($next, "right", "right", true); | |
} | |
my @successors = $graph->successors($root); | |
for my $s (@successors){ | |
if($graph->has_edge_attribute($root, $s, "left")){ | |
insert($graph, $s, $next); | |
} | |
} | |
} | |
if($root < $next){ | |
if($graph->has_edge_attribute($root, "right", "right")){ | |
$graph->delete_edge_attributes($root, "right"); | |
$graph->set_edge_attribute($root, $next, "right", true); | |
$graph->set_edge_attribute($next, "left", "left", true); | |
$graph->set_edge_attribute($next, "right", "right", true); | |
} | |
my @successors = $graph->successors($root); | |
for my $s (@successors){ | |
if($graph->has_edge_attribute($root, $s, "right")){ | |
insert($graph, $s, $next); | |
} | |
} | |
} | |
} | |
sub find_path_sum{ | |
my($graph, $sum, $path) = @_; | |
my $parent = $path->[-1]; | |
my @children = $graph->successors($parent); | |
for my $v (@children){ | |
push @{$path}, $v; | |
my $total = unpack("%32C*", pack("C*", @{$path})); | |
if($total == $sum && $graph->is_sink_vertex($v)){ | |
return $path; | |
} | |
else{ | |
my @p = @{$path}; | |
$path = find_path_sum($graph, $sum, \@p) if @p; | |
if($path){ | |
my $total = unpack("%32C*", pack("C*", @{$path})); | |
return $path if $total == $sum; | |
} | |
} | |
} | |
} | |
sub display_path{ | |
my($graph, $path) = @_; | |
my $s = $graph->stringify(); | |
for my $v (@{$path}){ | |
my $v_ = "$v*"; | |
$s =~ s/$v/$v_/g; | |
} | |
my @s = split(/,/, $s); | |
my @lines; | |
for my $n (@s){ | |
my @a = split(/-/, $n); | |
push @lines, "[ $a[0] ] => [ $a[1] ]"; | |
} | |
my $parser = new Graph::Easy::Parser(); | |
my $graph_viz = $parser->from_text(join("", @lines)); | |
print $graph_viz->as_ascii(); | |
#print $graph_viz->as_graphviz(); | |
} | |
MAIN:{ | |
my $graph = new Graph(multivertexed => true); | |
my @a = (11, 6, 8, 19, 4, 10, 5, 17, 43, 49, 31); | |
my $root; | |
for my $a (@a){ | |
if(!$root){ | |
$root = insert($graph, $root, $a) | |
} | |
else{ | |
insert($graph, $root, $a) | |
} | |
} | |
while($graph->has_vertex("left") && $graph->has_vertex("right")){ | |
$graph->delete_vertices("left", "right"); | |
} | |
my $path = find_path_sum($graph, SUM, [$root]); | |
display_path($graph, $path); | |
} |
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