/**
 * Given an array of characters chars, compress it using the following algorithm:
 *
 * Begin with an empty string s. For each group of consecutive repeating characters in chars:
 *
 * If the group's length is 1, append the character to s.
 * Otherwise, append the character followed by the group's length.
 * The compressed string s should not be returned separately, but instead, be stored in the input character array chars.
 * Note that group lengths that are 10 or longer will be split into multiple characters in chars.
 *
 * After you are done modifying the input array, return the new length of the array.
 *
 * You must write an algorithm that uses only constant extra space.
 *
 *
 *
 * Example 1:
 *
 * Input: chars = ["a","a","b","b","c","c","c"]
 * Output: Return 6, and the first 6 characters of the input array should be: ["a","2","b","2","c","3"]
 * Explanation: The groups are "aa", "bb", and "ccc". This compresses to "a2b2c3".
 * Example 2:
 *
 * Input: chars = ["a"]
 * Output: Return 1, and the first character of the input array should be: ["a"]
 * Explanation: The only group is "a", which remains uncompressed since it's a single character.
 * Example 3:
 *
 * Input: chars = ["a","b","b","b","b","b","b","b","b","b","b","b","b"]
 * Output: Return 4, and the first 4 characters of the input array should be: ["a","b","1","2"].
 * Explanation: The groups are "a" and "bbbbbbbbbbbb". This compresses to "ab12".
 *
 *
 * Constraints:
 *
 * 1 <= chars.length <= 2000
 * chars[i] is a lowercase English letter, uppercase English letter, digit, or symbol.
 * @see <a href="https://leetcode.com/problems/string-compression/">LeetCode</a>
 */
fun compress(chars: CharArray): Int {
    var answerIndex = 0
    var currentIndex = 0
    while (currentIndex < chars.size) {
        val currentCharacter = chars[currentIndex]
        var count = 0
        while (currentIndex < chars.size && chars[currentIndex] == currentCharacter) {
            currentIndex++
            count++
        }
        chars[answerIndex++] = currentCharacter
        if (count > 1) {
            count.toString().forEach { digit ->
                chars[answerIndex++] = digit
            }
        }
    }
    return answerIndex
}
