648. Replace Words

648. Replace Words

Medium

In English, we have a concept called root, which can be followed by some other word to form another longer word - let's call this word derivative. For example, when the root "help" is followed by the word "ful", we can form a derivative "helpful".

Given a dictionary consisting of many roots and a sentence consisting of words separated by spaces, replace all the derivatives in the sentence with the root forming it. If a derivative can be replaced by more than one root, replace it with the root that has the shortest length.

Return the sentence after the replacement.

Example 1:

• Input: dictionary = ["cat","bat","rat"], sentence = "the cattle was rattled by the battery"
• Output: "the cat was rat by the bat"

Example 2:

• Input: dictionary = ["a","b","c"], sentence = "aadsfasf absbs bbab cadsfafs"
• Output: "a a b c"

Constraints:

• 1 <= dictionary.length <= 1000
• 1 <= dictionary[i].length <= 100
• dictionary[i] consists of only lower-case letters.
• 1 <= sentence.length <= 106
• sentence consists of only lower-case letters and spaces.
• The number of words in sentence is in the range [1, 1000]
• The length of each word in sentence is in the range [1, 1000]
• Every two consecutive words in sentence will be separated by exactly one space.
• sentence does not have leading or trailing spaces.

Solution:

class Solution {

    private $root;
    public function __construct() {
        $this->root = new TrieNode();
    }

    /**
     * @param String[] $dictionary
     * @param String $sentence
     * @return String
     */
    function replaceWords($dictionary, $sentence) {
        foreach ($dictionary as $word) {
            $this->insert($word);
        }

        $ans = '';
        $iss = explode(' ', $sentence);

        foreach ($iss as $s) {
            $ans .= $this->search($s) . ' ';
        }
        $ans = rtrim($ans);

        return $ans;
    }

    private function insert($word) {
        $node = $this->root;
        for ($i = 0; $i < strlen($word); $i++) {
            $c = $word[$i];
            $index = ord($c) - ord('a');
            if ($node->children[$index] == null) {
                $node->children[$index] = new TrieNode();
            }
            $node = $node->children[$index];
        }
        $node->word = $word;
    }

    private function search($word) {
        $node = $this->root;
        for ($i = 0; $i < strlen($word); $i++) {
            $c = $word[$i];
            if ($node->word != null) {
                return $node->word;
            }
            $index = ord($c) - ord('a');
            if ($node->children[$index] == null) {
                return $word;
            }
            $node = $node->children[$index];
        }
        return $word;
    }
}

class TrieNode {
    public $children;
    public $word;

    public function __construct() {
        $this->children = array_fill(0, 26, null);
        $this->word = null;
    }
}

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