【done+重点】剑指offer56-II：数组中数字出现的次数

力扣，https://leetcode.cn/problems/shu-zu-zhong-shu-zi-chu-xian-de-ci-shu-ii-lcof/description/
思路：https://leetcode.cn/problems/shu-zu-zhong-shu-zi-chu-xian-de-ci-shu-ii-lcof/solutions/215895/mian-shi-ti-56-ii-shu-zu-zhong-shu-zi-chu-xian-d-4/
有限状态自动机推导式太复杂，略去~

class Solution {
    public int trainingPlan(int[] actions) {
        int res = 0, m = 3;
        int[] counter = new int[32]; // java中int型数据包含4个byte, 1byte=8bit, 共32位;最高位是符号位
        for (int act : actions) {
            for (int i = 0; i < 32; ++i) {
                counter[i] += act & 1;
                act >>= 1;
            }
        }

        for (int i = 31; i >= 0; --i) {
            res <<= 1;
            res += counter[i] % m; // 这俩顺序不能颠倒, 否则会导致最后往左多挪动1位
        }

        return res;
    }
}