A-M baby

Task/Huffman-coding/PHP/huffman-coding.php

@@ -0,0 +1,28 @@
+<?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";
+?>