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Huffman coding: Difference between revisions
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x 01111
h 11111</pre>
=={{header|PHP}}==
{{works with|PHP|5.3+}}
{{trans|Python}} (not exactly)
<lang php><?php
function encode($symb2freq) {
$heap = new SplPriorityQueue;
$heap->setExtractFlags(SplPriorityQueue::EXTR_BOTH);
foreach ($symb2freq as $sym => $wt)
$heap->insert(array($sym => ''), -$wt);
while ($heap->count() > 1) {
$lo = $heap->extract();
$hi = $heap->extract();
foreach ($lo['data'] as &$x)
$x = '0'.$x;
foreach ($hi['data'] as &$x)
$x = '1'.$x;
$heap->insert($lo['data'] + $hi['data'],
$lo['priority'] + $hi['priority']);
}
$result = $heap->extract();
return $result['data'];
}
$txt = 'this is an example for huffman encoding';
$symb2freq = array_count_values(str_split($txt));
$huff = encode($symb2freq);
echo "Symbol\tWeight\tHuffman Code\n";
foreach ($huff as $sym => $code)
echo "$sym\t$symb2freq[$sym]\t$code\n";
?></lang>
Example output:
<pre>
Symbol Weight Huffman Code
n 4 000
m 2 0010
o 2 0011
t 1 01000
g 1 01001
x 1 01010
u 1 01011
s 2 0110
c 1 01110
d 1 01111
p 1 10000
l 1 10001
a 3 1001
6 101
f 3 1100
i 3 1101
r 1 11100
h 2 11101
e 3 1111
</pre>
=={{header|Prolog}}==
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