Tetris-ing an array

Question

Consider the following array:

/www/htdocs/1/sites/lib/abcdedd
/www/htdocs/1/sites/conf/xyz
/www/htdocs/1/sites/conf/abc/         


        

Answer 1

A naive approach would be to explode the paths at the / and successive compare every element in the arrays. So e.g. the first element would be empty in all arrays, so it will be removed, the next element will be www, it is the same in all arrays, so it gets removed, etc.

Something like (untested)

$exploded_paths = array();

foreach($paths as $path) {
    $exploded_paths[] = explode('/', $path);
}

$equal = true;
$ref = &$exploded_paths[0]; // compare against the first path for simplicity

while($equal) {   
    foreach($exploded_paths as $path_parts) {
        if($path_parts[0] !== $ref[0]) {
            $equal = false;
            break;
        }
    }
    if($equal) {
        foreach($exploded_paths as &$path_parts) {
            array_shift($path_parts); // remove the first element
        }
    }
}

Afterwards you just have to implode the elements in $exploded_paths again:

function impl($arr) {
    return '/' . implode('/', $arr);
}
$paths = array_map('impl', $exploded_paths);

Which gives me:

Array
(
    [0] => /lib/abcdedd
    [1] => /conf/xyz
    [2] => /conf/abc/def
    [3] => /htdocs/xyz
    [4] => /conf/xyz
)

This might not scale well ;)