<php function binarySearch($arr,$a){ $low = 0; $high = count($arr)-1; $mid = ceil(($low+$high)/2);while($low<=$high){ if($a==$arr[$mid]){ echo "查找的数的位置是第"."$mid"; } if($a>$arr[$mid]){ $high = count($arr)-1; $low = $mid+1; $mid = ceil(($low+$high)/2); } if ($a<$arr[$mid]) { $low = 0; $high = $mid-1; $mid = ceil(($low+$high)/2); } }}$arr1 = array(5,7,9,10,12,16,19);binarySearch($arr1,12);?>
function binarySearch($arr,$a){
$low = 0;
$high = count($arr)-1;
$mid = ceil(($low+$high)/2);
$n = 0;防止死循环的措施
while($low<=$high && $n++
echo "查找的数的位置是第"."$mid";
break;
}
if($a>$arr[$mid]){
$high = count($arr)-1;
$low = $mid -1; //注意这里
$mid = ceil(($low+$high)/2);
}
if ($a<$arr[$mid]) {
$low = 0;
$high = $mid +1; //注意这里
$mid = ceil(($low+$high)/2);
}
}
}
按 php 实际可写作
function binarySearch($arr,$a){ $low = 0; $high = count($arr)-1; $mid = ceil(($low+$high)/2); $num = count($arr); while($low<=$high && $num--){ if($a==$arr[$mid]){ echo "查找的数的位置是第"."$mid"; break; } list($low, $high) = $a > $arr[$mid] ? array($mid, $high) : array($low, $mid); $mid = ceil(($low+$high)/2); }} 本帖最后由 xuzuning 于 2013-03-30 17:42:33 编辑
function binarySearch($arr,$a){
$low = 0;
$high = count($arr)-1;
$mid = ceil(($low+$high)/2);
$n = 0;防止死循环的措……
我有点晕 如果是四个数呢，比如$r=array(1,2,3,4) 查找1 貌似不行 用floor来求$mid 这个 我 理解，用ceil貌似 有点问题、、、、
按 php 实际可写作
PHP code?1234567891011121314function binarySearch($arr,$a){ $low = 0; $high = count($arr)-1; $mid = ceil(($low+$high)/2); $num = count($arr); while($low<=$high &&……[/quote
还是要 谢谢 版主大大、、、
function binarySearch($arr,$a){ $low = 0; $high = count($arr)-1; $mid = ceil(($low+$high)/2); $loop = count($arr); while($low<$high-1 && $loop--){ if($a==$arr[$mid]){ echo "查找的数的位置是第"."$mid"; return $mid; } list($low, $high) = $a>$arr[$mid] ? array($mid, $high) : array($low, $mid); $mid = ceil(($low+$high)/2); } echo "查找的数的位置在第{$low}、{$high}之间";}$arr1 = array(5,7,9,10,12,16,19);binarySearch($arr1,11);
