public function execute() { $arr = range(1, 100); $arr[] = 97; shuffle($arr); $i = 0; while($i < count($arr)) { if($i == $arr[$i]) { $i++; continue; } if($arr[$i] == $arr[$arr[$i]]) { echo ($arr[$i]); exit(); } $tmp = $arr[$i]; $arr[$i] = $arr[$tmp]; $arr[$tmp] = $tmp; //key = value放齐 } }