php 笛卡尔积的实现

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<?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
)

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原文：https://blog.csdn.net/free_ant/article/details/52671108 
 

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