<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);
$num = count($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+$high)/2);
}
}
我有点晕 如果是四个数呢,比如$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、、、、
$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);