数组排列算法笔试题

Question

php算法笔试题

有一二维数组

array(array(1,2,3,4,5,6,7,8,9),
      array(1,2,3,4,5,6,7,8,9),
      array(1,2,3,4,5,6,7,8,9),    
      array(1,2,3,4,5,6,7,8,9),    
      array(1,2,3,4,5,6,7,8,9),        
      )

每个数组取不同的5个数为组成1组 求问有多少种组合
数组[数组0]取出的值 != 数组[数组1]取出的值!= 数组[数组2]取出的值 != 数组[数组3]取出的值 != 数组[数组4]取出的值 组成一组;
为一组
这种
求解

Answer 1

for ($i = 1; $i < 10; $i++) { for ($j = 1; $j < 10; $j++) { if ($i == $j) { continue; } for ($k = 1; $k < 10; $k++) { if ($i == $k || $j == $k) { continue; } for ($l = 1; $l < 10; $l++) { if ($i == $l || $j == $l || $k == $l) { continue; } for ($m = 1; $m < 10; $m++) { if ($i == $m || $j == $m || $k == $m || $l == $m) { continue; } $arr[] = $i . $j . $k . $l . $m; } } } } } echo '<pre>'; var_dump($arr);die(); //方法二 //不过可以应对不同的数组参数，不过参数越多，性能就越糟糕 set_time_limit(0); $arr =[ [1,2,3,4,5,6,7,8,9], [1,2,3], [1,2,3,4,5,6,7,8,9], [1,2,3,4,5,6,7,8,9], [1,2,3,4,5,6,7,8,9], [5,6,7,8,9], ]; $count = count($arr); //需求：$arr每个子数组取出一个1个不同的数，进行组合 $main = []; for($i=0; $i<$count; $i++){ $dep = $arr[$i]; $sock = $main; $main = []; for ($j=0; $j <count($sock) ; $j++) { $split = str_split($sock[$j]); for ($k=0; $k < count($dep); $k++) { if(in_array($dep[$k], $split)){ continue; } $number = $sock[$j].$dep[$k]; if(!in_array($number, $main)){ $main[]=$number; } } } $main = empty($main)?$dep:$main; } echo '<pre>'; var_dump($main); die();

Answer 2

9×8×7×6×5 = 15120;应该是这样的吧

Answer 3

9x8x7x6x5

Answer 4

98765