分块查找算法 (php)

来源：互联网发布：ubuntu启动程序命令编辑：程序博客网时间：2024/06/12 05:23
class Node{    public $data; // 数据域    public $key; // 关键之查找}class IndexNode{    public $key; // 记录当前快中最大的key数    public $link; // 当地块的起始地址}function InitIndex(SplFixedArray $seqList){    $n = $seqList->count();    $s = ceil(sqrt($n));    $b = $s;    $indexList = new SplFixedArray($b);    for ($i = 0; $i < $s; $i ++) {        $max = null;        for ($j = 0; $j < $s; $j ++) {            if ($i * $s + $j < $n && $max < $seqList[$i * $s + $j]->key) {                $max = $seqList[$i * $s + $j]->key;            }        }        $idx = new IndexNode();        $idx->key = $max;        $idx->link = $i * $s;        $indexList[$i] = $idx;    }    return $indexList;}function searchIndex(SplFixedArray $seqList, SplFixedArray $indexList, $val){    $n = $seqList->count();    $m = ceil(sqrt($n));        for ($i = 0; $i < $m; $i ++) {        if ($seqList[$indexList[$i]->key]->data < $val)            continue;        $j = $indexList[$i]->link;        $end = $j + $m;        while ($j <= $end && $seqList[$j]->data != $val) {            $j ++;        }        if ($j > $end) {            continue;        } else {            return $j;        }    }    return -1;}$arr=[14,27,32,50,10,76,32,55,44,33,9,96,30,57,49];$seqList = new SplFixedArray(count($arr));for($i=0;$i<count($arr);$i++){    $node=new Node();    $node->key=$i;    $node->data=$arr[$i];    $seqList[$i]=$node;}$indexList = InitIndex($seqList);$index=searchIndex($seqList, $indexList, 55);print_r($index);
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