Decoding anagram with recursive function doesn't give expected output - php

Question

So I'm trying to decode an anagram into words from my dictionary file. But my recursive function isn't behaving like I'm expecting.
The thoughts about the code is to eliminate letters as they are used on words and output me the string it came up with.
<?php
function anagram($string, $wordlist)
{
if(empty($string))
return;
foreach($wordlist as $line)
{
$line = $org = trim($line);
$line = str_split($line);
sort($line);
foreach($line as $key => $value)
{
if($value != $string[$key])
{
continue 2;
}
}
echo $org . anagram(array_slice($string, count($line)), $wordlist);
}
echo PHP_EOL;
}
$string = "iamaweakishspeller";
$string = str_split($string);
sort($string);
$file = file('wordlist');
anagram($string, $file);
This is my result for now, it looks awful, but I'm having some issues with the code - it's going into an indefinite loop with the same roughly 200 words from the word list.
Can someone take an extra peak at this?

Answer 1

Situation
You have a dictionary(file) and an anagram which contains one or multiple words. The anagram doesn't contain any punctuation or letter case of the original word(s).
Now you want to find all true solutions where you use up all characters of the anagram and decode it into word(s) from the dictionary.
Note: There is a chance that you find multiple solutions and you will never know which one the original text was and in which order the words were, since the characters of multiple words are mixed in the anagram and you don't have punctuation or the case of the letters in it.
Your code
The problem in your current code is exactly that you have multiple words mixed together. If you sort them now and you want to search them in the dictionary you won't be able to find them, since the characters of multiple words are mixed. Example:
anagram = "oatdgc" //"cat" + "dog"
wordList = ["cat", "dog"]
wordListSorted = ["act", "dgo"]
anagramSorted = acdgot
↓↓↓
WordListSorted[0] → cat ✗ no match
WordListSorted[1] → dog ✗ no match
Solution
First I will explain in theory how we construct all possible true solutions and then I explain how every part in the code works.
Theory
So to start we have an anagram and a dictionary. Now we first filter the dictionary by the anagram and only keep the words, which can be constructed by the anagram.
Then we go through all words and for each word we add it to a possible solution, remove it from the anagram, filter the dictionary by the new anagram and call the function with the new values recursively.
We do this until either the anagram is empty and we found a true solution, which we add to our solution collection, or there are no words remaining and it is not a possible solution.
Code
We have two helper functions array_diff_once() and preSelectWords() in our code.
array_diff_once() is pretty much the same as the built-in array_diff() function, except that it only removes values once and not all occurrences. Otherwise there isn't much to explain. It simply loops through the second array and removes the values once in the first array, which then gets returned.
function array_diff_once($arrayOne, $arrayTwo){
foreach($arrayTwo as $v) {
if(($key = array_search($v, $arrayOne)) !== FALSE)
array_splice($arrayOne, $key, 1);
}
return $arrayOne;
}
preSelectWords() takes an anagram and a word list as argument. It simply checks with the help of array_diff_once(), which words of the word list can be constructed with the given anagram. Then it returns all possible words from the word list, which can be constructed with the anagram.
function preSelectWords($anagram, $wordList){
$tmp = [];
foreach($wordList as $word){
if(!array_diff_once(str_split(strtolower($word)), $anagram))
$tmp[] = $word;
}
return $tmp;
}
Now to the main function decodeAnagram(). We pass the anagram and a word list, which we first filter with preSelectWords(), as arguments to the function.
In the function itself we basically just loop through the words and for each word we remove it from the anagram, filter the word list by the new anagram and add the word to a possible solution and call the function recursively.
We do this until either the anagram is empty and we found a true solution, which we add to our solution array, or there are no words left in the list and with that no possible solution.
function decodeAnagram($anagram, $wordList, $solution, &$solutions = []){
if(empty($anagram) && sort($solution) && !isset($solutions[$key = implode($solution)])){
$solutions[$key] = $solution;
return;
}
foreach($wordList as $word)
decodeAnagram(array_diff_once($anagram, str_split(strtolower($word))), preSelectWords(array_diff_once($anagram, str_split(strtolower($word))), $wordList), array_merge($solution, [$word]), $solutions);
}
Code
<?php
function decodeAnagram($anagram, $wordList, $solution, &$solutions = []){
if(empty($anagram) && sort($solution) && !isset($solutions[$key = implode($solution)])){
$solutions[$key] = $solution;
return;
}
foreach($wordList as $word)
decodeAnagram(array_diff_once($anagram, str_split(strtolower($word))), preSelectWords(array_diff_once($anagram, str_split(strtolower($word))), $wordList), array_merge($solution, [$word]), $solutions);
}
function preSelectWords($anagram, $wordList){
$tmp = [];
foreach($wordList as $word){
if(!array_diff_once(str_split(strtolower($word)), $anagram))
$tmp[] = $word;
}
return $tmp;
}
function array_diff_once($arrayOne, $arrayTwo){
foreach($arrayTwo as $v) {
if(($key = array_search($v, $arrayOne)) !== FALSE)
array_splice($arrayOne, $key, 1);
}
return $arrayOne;
}
$solutions = [];
$anagram = "aaaeeehiikllmprssw";
$wordList = ["I", "am", "a", "weakish", "speller", "William", "Shakespeare", "other", "words", "as", "well"];
//↑ file("wordlist", FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES)
decodeAnagram(str_split(strtolower($anagram)), preSelectWords(str_split(strtolower($anagram)), $wordList), [], $solutions);
print_r($solutions);
?>
Output
Array
(
[Iaamspellerweakish] => Array
(
[0] => I
[1] => a
[2] => am
[3] => speller
[4] => weakish
)
[ShakespeareWilliam] => Array
(
[0] => Shakespeare
[1] => William
)
)
(Ignore the keys here, since those are the identifiers of the solutions)