php数据结构与算法(PHP描述) 查找与二分法查找
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<div class="codetitle"><a style="CURSOR: pointer" data="54070" class="copybut" id="copybut54070" onclick="doCopy('code54070')"> 代码如下:
<div class="codebody" id="code54070">
<?
PHP /
查找
/
// 顺序查找
function normal_search($arrData,$val) {
$len = count($arrData);
if($len == 0) return -1;
for($i = 0;$i < $len; $i++ ) {
echo "find No.",$i + 1," value = ",$arrData[$i]," is = ",$val,"?
";
// 找到了
if($arrData[$i] == $val) return $i;
}
return -1;
} // 测试顺序查找
$arrData = array(4,51,6,73,2,5,9,33,50,3,4,1,67);
echo normal_search($arrData,6),"
";
echo normal_search($arrData,66),"
"; // 二分法查找(针对有序的列进行查找)
function binary_search($arrData,$val) {
$len = count($arrData);
if($len == 0) return -1; $start = 0;
$end = $len - 1; while($start <= $end) {
$middle = intval(($start + $end)/2);
echo "start = ",$start," end = ",$end," middle = ",$middle,"
";
if($arrData[$middle] == $val) {
return $middle;
} elseif ($arrData[$middle] > $val) {
$end = $middle - 1 ;
} elseif ($arrData[$middle] < $val) {
$start = $middle + 1;
}
}
return -1;
} // 测试一下二分法查找
$arrData = array(1,7,8,11,23,56,100,104,578,1000);
echo binary_search($arrData,578),"
";
echo binary_search($arrData,"
";
