1002. Find Common Characters

/**
 * 1002. Find Common Characters
 * https://leetcode.com/problems/find-common-characters/submissions/
 * 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"]
 * */
class Solution {
    fun commonChars(A: Array<String>): List<String> {
        val result = ArrayList<String>()
        val map = HashMap<Char, IntArray>()
        for (i in 0..(A.size - 1)) {
            for (c in A[i]) {
                if (!map.containsKey(c)) {
                    map.put(c, IntArray(A.size))
                }
                //array数组保存为:出现过的char在每一个A的子数组中出现的次数，顺序对应着A的子数组
                //如a在"bella","label","roller",对应为[1,1,0]
                val array = map.get(c)!!
                array[i]++
                map.put(c, array)
            }
        }
        map.forEach { key, charCountArr ->
            var canInsertFlag = 0
            for (v in charCountArr) {
                canInsertFlag += v
            }
            var canInsert = canInsertFlag >= A.size
            if (canInsert) {
                charCountArr.sort()
                var insertCount = charCountArr[0]
                for (j in 0..(insertCount - 1)) {
                    result.add(key.toString())
                }
            }
        }
        return result
    }
}