PHP笛卡尔积实现算法示例

本文实例讲述了PHP笛卡尔积实现算法。分享给大家供大家参考，具体如下：

<?php$arr = array(array(1,3,4,5),array(3,5,7,9),array(76,6,1,0));/**** 实现二维数组的笛卡尔积组合** $arr 要进行笛卡尔积的二维数组** $str 最终实现的笛卡尔积组合,可不写** @return array**/function cartesian($arr,$str = array()){  //去除第一个元素  $first = array_shift($arr);  //判断是否是第一次进行拼接  if(count($str) > 1) {    foreach ($str as $k => $val) {      foreach ($first as $key => $value) {        //最终实现的格式 1,3,76        //可根据具体需求进行变更        $str2[] = $val.','.$value;      }    }  }else{    foreach ($first as $key => $value) {      //最终实现的格式 1,3,76      //可根据具体需求进行变更      $str2[] = $value;    }  }  //递归进行拼接  if(count($arr) > 0){    $str2 = cartesian($arr,$str2);  }  //返回最终笛卡尔积  return $str2;}$cartesian_product = cartesian($arr);print_r($cartesian_product);?>

最终输出格式

Array
(
    [0] => 1,3,76
    [1] => 1,3,6
    [2] => 1,3,1
    [3] => 1,3,0
    [4] => 1,5,76
    [5] => 1,5,6
    [6] => 1,5,1
    [7] => 1,5,0
    [8] => 1,7,76
    [9] => 1,7,6
    [10] => 1,7,1
    [11] => 1,7,0
    [12] => 1,9,76
    [13] => 1,9,6
    [14] => 1,9,1
    [15] => 1,9,0
    [16] => 3,3,76
    [17] => 3,3,6
    [18] => 3,3,1
    [19] => 3,3,0
    [20] => 3,5,76
    [21] => 3,5,6
    [22] => 3,5,1
    [23] => 3,5,0
    [24] => 3,7,76
    [25] => 3,7,6
    [26] => 3,7,1
    [27] => 3,7,0
    [28] => 3,9,76
    [29] => 3,9,6
    [30] => 3,9,1
    [31] => 3,9,0
    [32] => 4,3,76
    [33] => 4,3,6
    [34] => 4,3,1
    [35] => 4,3,0
    [36] => 4,5,76
    [37] => 4,5,6
    [38] => 4,5,1
    [39] => 4,5,0
    [40] => 4,7,76
    [41] => 4,7,6
    [42] => 4,7,1
    [43] => 4,7,0
    [44] => 4,9,76
    [45] => 4,9,6
    [46] => 4,9,1
    [47] => 4,9,0
    [48] => 5,3,76
    [49] => 5,3,6
    [50] => 5,3,1
    [51] => 5,3,0
    [52] => 5,5,76
    [53] => 5,5,6
    [54] => 5,5,1
    [55] => 5,5,0
    [56] => 5,7,76
    [57] => 5,7,6
    [58] => 5,7,1
    [59] => 5,7,0
    [60] => 5,9,76
    [61] => 5,9,6
    [62] => 5,9,1
    [63] => 5,9,0
)

小编这里参考前面一篇《JavaScript笛卡尔积超简单实现算法》，给出一个php计算笛卡尔积的超简单算法示例如下：

<?phpfunction cartesian($arr1,$arr2){  $relarr = array();  foreach($arr1 as $v1){    foreach($arr2 as $v2){      array_push($relarr,$v1.",".$v2);    }  }  return $relarr;}//用法示例$a = array('1','2','3');$b = array('a','b',c);print_r(cartesian($a,$b));?>

运行结果：

Array
(
    [0] => 1,a
    [1] => 1,b
    [2] => 1,c
    [3] => 2,a
    [4] => 2,b
    [5] => 2,c
    [6] => 3,a
    [7] => 3,b
    [8] => 3,c
)

希望本文所述对大家PHP程序设计有所帮助。