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871天前<?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 = ",$val,"? <br/>"; |
// 找到了 |
if($arrData[$i] == $val) return $i; |
} |
return -1; |
} |
// 测试顺序查找 |
$arrData = array(4,51,6,73,2,5,9,33,50,3,4,6,1,4,67); |
echo normal_search($arrData,6),"<br/>"; |
echo normal_search($arrData,66),"<br/>"; |
// 二分法查找(针对有序的列进行查找) |
function binary_search($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,"<br/>"; |
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 |
$arrData = array(1,2,3,4,5,7,8,9,11,23,56,100,104,578,1000); |
echo binary_search($arrData,578),"<br/>"; |
echo binary_search($arrData,66),"<br/>"; |
