我的任务是使用8个块中的数据创建所有可能性的列表.
8个街区有以下几种可能性：
*Block 1: 12 possibilities *Block 2: 8 possibilities *Block 3: 8 possibilities *Block 4: 11 possibilities *Block 5: 16 possibilities *Block 6: 11 possibilities *Block 7: 5 possibilities *Block 8: 5 possibilities
这提供了潜在的37,171,200种可能性.
我只是尝试并限制只显示返回的值与正确的字符串长度,如下所示：
foreach($block1 AS $b1){
foreach($block2 AS $b2){
foreach($block3 AS $b3){
foreach($block4 AS $b4){
foreach($block5 AS $b5){
foreach($block6 AS $b6){
foreach($block7 AS $b7){
foreach($block8 AS $b8){
if (strlen($b1.$b2.$b3.$b4.$b5.$b6.$b7.$b8) == 16)
{
echo $b1.$b2.$b3.$b4.$b5.$b6.$b7.$b8.'<br/>';
}
}
}
}
}
}
}
}
}
但是,执行时间太长,无法计算.我想知道是否有人知道更简单的方法吗？
您可以通过缓存字符串前缀并记住它们的长度来改进算法.然后,您不必为每个组合执行此操作.
$len = 16:
// array for remaining characters per level
$r = array($len);
// array of level parts
$p = array();
foreach ($block1 AS &$b1) {
// skip if already too long
if (($r[0] - strlen($b1)) <= 0) continue;
$r[1] = $r[0] - strlen($b1);
foreach ($block2 AS &$b2) {
if (($r[1] - strlen($b2)) <= 0) continue;
$r[2] = $r[1] - strlen($b2);
foreach ($block3 AS $b3) {
// …
foreach ($block8 AS &$b8) {
$r[8] = $r[7] - strlen($b8);
if ($r[8] == 0) {
echo implode('',$p).'<br/>';
}
}
}
}
}
此外,在foreach中使用引用将在内部使用数组副本来停止PHP.