Heapsort is a member of selection sort family. Although somewhat slower in practice on most machines than a well implemented quicksort, it has the advantage of a more favorable worst-case O(n log n) runtime. Heapsort is an in-place algorithm, but is not a stable sort.

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`<?php function build_heap(&$array, $i, $t){ $tmp_var = $array[$i]; $j = $i * 2 + 1; while ($j <= $t) { if($j < $t) if($array[$j] < $array[$j + 1]) { $j = $j + 1; } if($tmp_var < $array[$j]) { $array[$i] = $array[$j]; $i = $j; $j = 2 * $i + 1; } else { $j = $t + 1; } } $array[$i] = $tmp_var; } function heap_sort(&$array) { //This will heapify the array`

$init = (int)floor((count($array) - 1) / 2);`// Thanks jimHuang for bug report for($i=$init; $i >= 0; $i--){ $count = count($array) - 1; build_heap($array, $i, $count); } //swaping of nodes for ($i = (count($array) - 1); $i >= 1; $i--) { $tmp_var = $array[0]; $array [0] = $array [$i]; $array [$i] = $tmp_var; build_heap($array, 0, $i - 1); } } // Demo $array = array(9,8,7,6,5,4,3,2,1,0,10,1000,0); heap_sort($array); print_r($array); ?>`

There is a bug:

ReplyDelete$init = (count($array) - 1) / 2;

Should be:

$init = (int)floor((count($array) - 1) / 2);

Thanks for reporting.

DeleteNice blog...Very useful information is providing by ur blog. Great beginning php tutorials Very clear and helpful for beginners.

ReplyDelete