OddStringDifference.php

<?php

namespace App;

/**
 * Odd String Difference
 *
 * You are given an array of equal-length strings words. Assume that the length of each string is n. Each string
 * words[i] can be converted into a difference integer array difference[i] of length n - 1 where
 * difference[i][j] = words[i][j+1] - words[i][j] where 0 <= j <= n - 2. Note that the difference between two letters
 * is the difference between their positions in the alphabet i.e. the position of 'a' is 0, 'b' is 1, and 'z' is 25.
 * For example, for the string "acb", the difference integer array is [2 - 0, 1 - 2] = [2, -1].
 * All the strings in words have the same difference integer array, except one. You should find that string.
 * Return the string in words that has different difference integer array.
 *
 * Example 1:
 * Input: words = ["adc","wzy","abc"]
 * Output: "abc"
 * Explanation:
 * - The difference integer array of "adc" is [3 - 0, 2 - 3] = [3, -1].
 * - The difference integer array of "wzy" is [25 - 22, 24 - 25]= [3, -1].
 * - The difference integer array of "abc" is [1 - 0, 2 - 1] = [1, 1].
 * The odd array out is [1, 1], so we return the corresponding string, "abc".
 *
 * Example 2:
 * Input: words = ["aaa","bob","ccc","ddd"]
 * Output: "bob"
 * Explanation: All the integer arrays are [0, 0] except for "bob", which corresponds to [13, -13].
 *
 * https://leetcode.com/problems/odd-string-difference
 */
class OddStringDifference
{
    /**
     * @param string[] $words
     * @return string
     */
    public function oddString(array $words): string
    {
        $res = $arr = [];
        foreach ($words as $key => $value) {
            $tmp = str_split($value);
            for ($i = 1, $iMax = count($tmp); $i < $iMax; $i++) {
                $arr[$i - 1] = ord($tmp[$i]) - ord($tmp[$i - 1]);
            }
            $res[$key] = serialize($arr);
        }

        return $words[array_search(array_search(1, array_count_values($res), true), $res, true)];
    }
}