Possible grouping of words

问题

This is not homework: Came across this scenario while working on PHP String Differences and Dynamic Restrictions

Given a string of n words how to distribute them into m groups without altering the word sequence?

Example 1:
String: "My name is SparKot"
Groups: 2 (string is split in to two strings)

Possible groups will be:
('My', 'name is SparKot'), 
('My name', 'is SparKot'),
('My name is', 'SparKot')

with the same string

Example 2:
String: "My name is SparKot"
Groups: 3 (string will be split in to three strings)

Possible groups will be:
('My', 'name', 'is SparKot'),
('My', 'name is', 'SparKot'),
('My name', 'is', 'SparKot')

My PHP function() with no direction(it is suppose to return Multi-dimension of groups):

function get_possible_groups ($orgWords, $groupCount, &$status) {

    $words = explode (' ', $orgWords);
    $wordCount = count($words);

    if ($wordCount < $groupCount) {
        $status = -1;
        return;
    } else if ($wordCount === $groupCount) {
        $status = 0;
        return (array_chunk($words, 1));
    }

    for ($idx =0; $idx < $wordCount; $idx) {
        for ($jdx =0; $jdx < $groupCount; $jdx++) {

        }
    }
//  append all arrays to form multidimension array
//  return groupings[][] array
}
$status =0;

$groupings = get_possible_groups('My name is SparKot', 4, $status);

var_dump($groupings);

for above example-2 function is supposed to return:

$groupings = array (
        array ('My', 'name', 'is SparKot'),
        array ('My', 'name is', 'SparKot'),
        array ('My name', 'is', 'SparKot'));

Any hints to approach this problem will be much appreciated.

Progress:

case: when wordCount = groupCount [solved]

回答1:

Ok, so, it took me quite a while but I think I managed to get this right. I'm really proud, to be honest, since I don't usually do well with algorithms. Anyway, here we go:

function getPossibleGroups($string, $groups) {
    $words = explode(' ', $string);
    $wordCount = count($words);

    if ($groups === 1) {
        return array(array($string));
    } elseif ($groups > $wordCount) {
        return null;
    } elseif ($groups === $wordCount) {
        return array($words);
    }

    $results = array();
    // We get every possible result for the first group
    for ($i = 1; $i <= $wordCount - $groups + 1; $i++) {
        $firstGroup = implode(' ', array_slice($words, 0, $i));

        // Recursively get all posible results for the other groups
        $otherGroups = getPossibleGroups(implode(' ', array_slice($words, $i)), $groups - 1);

        // Merge both things
        $allGroups = array_map(function($v) use ($firstGroup) {
            return array_merge(array($firstGroup), $v);
        }, $otherGroups);

        // Add that to the results variable
        $results = array_merge($results, $allGroups);
    }

    return $results;
}

来源：https://stackoverflow.com/questions/15144811/possible-grouping-of-words

标签

php

arrays

algorithm

multidimensional-array

explode