FindCommonCharacters.js

// Source : https://leetcode.com/problems/find-common-characters/
// Author : Dean Shi
// Date   : 2019-03-10

/***************************************************************************************
 *
 * Given an array A of strings made only from lowercase letters, return a list of all
 * characters that show up in all strings within the list (including duplicates).  For
 * example, if a character occurs 3 times in all strings but not 4 times, you need to
 * include that character three times in the final answer.
 *
 * You may return the answer in any order.
 *
 * Example 1:
 *
 * Input: ["bella","label","roller"]
 * Output: ["e","l","l"]
 *
 * Example 2:
 *
 * Input: ["cool","lock","cook"]
 * Output: ["c","o"]
 *
 * Note:
 *
 * 1 <= A.length <= 100
 * 1 <= A[i].length <= 100
 * A[i][j] is a lowercase letter
 *
 ***************************************************************************************/

/**
 * @param {string[]} A
 * @return {string[]}
 */
var commonChars = function(A) {
    let result = A[0].split('')

    for (let i = 1; i < A.length; i++) {
        const map = {}
        for (let c of A[i]) {
            map[c] = (map[c] || 0) + 1
        }

        result = result.filter((c) => map[c] > 0 && map[c]--)
    }
    return result
};