FindSmallestLetterGreaterThanTarget.js

// Source : https://leetcode.com/problems/find-smallest-letter-greater-than-target
// Author : Dean Shi
// Date   : 2018-01-20

/***************************************************************************************
 *
 * Given a list of sorted characters letters containing only lowercase letters, and
 * given a target letter target, find the smallest element in the list that is larger
 * than the given target.
 *
 * Letters also wrap around.  For example, if the target is target = 'z' and letters = [
 * 'a', 'b'], the answer is 'a'.
 *
 * Examples:
 * Input:
 * letters = ["c", "f", "j"]
 * target = "a"
 * Output: "c"
 *
 * Input:
 * letters = ["c", "f", "j"]
 * target = "c"
 * Output: "f"
 *
 * Input:
 * letters = ["c", "f", "j"]
 * target = "d"
 * Output: "f"
 *
 * Input:
 * letters = ["c", "f", "j"]
 * target = "g"
 * Output: "j"
 *
 * Input:
 * letters = ["c", "f", "j"]
 * target = "j"
 * Output: "c"
 *
 * Input:
 * letters = ["c", "f", "j"]
 * target = "k"
 * Output: "c"
 *
 * Note:
 *
 * letters has a length in range [2, 10000].
 * letters consists of lowercase letters, and contains at least 2 unique letters.
 * target is a lowercase letter.
 *
 ***************************************************************************************/

/**
 * @param {character[]} letters
 * @param {character} target
 * @return {character}
 */
var nextGreatestLetter = function(letters, target) {
    const targetNum = target.charCodeAt(0)
    for (let l of letters) {
        if (l.charCodeAt(0) > targetNum) return l
    }
    return letters[0]
};