PHP二分尋找-遞迴與非遞迴的範例程式碼分享

PHP二分尋找-遞迴與非遞迴的範例程式碼分享

<?phpfunction binarySearch($arr, $val){$len = count($arr);if(!is_array($arr) || $len <= 0){return false;}if($val < $arr[0] || $val > $arr[$len-1]){return false;}$start = 0;$end = $len - 1;while($start <= $end){$mid = intval(( $end+$start )/2); //中間值if($arr[$mid] == $val){return $mid;}if($val < $arr[$mid]){$end = $mid - 1;}else{$start = $mid + 1;}}return false;}

遞迴實現：

<?php// 遞迴function binarySearch_r($arr, $low, $high, $key){$len = count($arr);if(!is_array($arr) || $len <= 0){return false;}if($key < $arr[0] || $key > $arr[$len-1]){return false;}if($low <= $high){$mid = intval( ($low+$high)/2 );if($arr[$mid] == $key){return true;}$func_name = FUNCTION;if($key < $arr[$mid]){return $func_name($arr, $low, $mid-1, $key);}else{return $func_name($arr, $mid+1, $high, $key);}}return false;}