20250624java面试总结

算法题：一个rpc请求，输入是map<String,List>
key是商品类别字符串（good/travel/hotel）
value是商品id
如果商品数量过多或者类别过多，会导致rpc请求耗时过长，出现尖刺，为了平滑请求时间，如果key超过3个或者value超过3个，则进行请求拆分，
输出为：List<Map<String, List>

示例：
输入：
{
“good”:[1,2,3,4],
“travel”:[11,12,13,14],
“hotel”:[21,22,23]
}
输出为：[
{ “good”:[1,2,3],
“travel”:[11,12,13],
“hotel”:[21,22,23]
},
{
“good”:[4],
“travel”:[14]
}
]

示例代码：

public class SliceRpcRequest {

    public static void main(String[] args) {
        Map<String,List<Long>> request = new HashMap<>();
        request.put("good", Arrays.asList(1L,2L,3L,4L,5L,6L));
        request.put("travel", Arrays.asList(99L,92L,93L,94L,95L,96L,97L,98L));
        request.put("hotel", Arrays.asList(88L));
        request.put("ticket", Arrays.asList(1000L,10000L, 1233424L,123434L));
        List<Map<String,List<Long>>> res = sliceRequest(request);
        for (int i = 0; i < res.size(); i++) {
            Map<String, List<Long>> map = res.get(i);
            System.out.println("=========");
            for (Map.Entry<String,List<Long>> entry : map.entrySet()) {
                System.out.println(entry.getKey() + ":" + Arrays.toString(entry.getValue().toArray()));
            }
        }
    }


    public static List<Map<String, List<Long>>> sliceRequest(Map<String, List<Long>> request) {
        List<Map<String, List<Long>>> list = new ArrayList<>();
        int index = 0;
        //     // good:1,2,3,4,5,6
        //    // travel: 99,92,93,94,95,96,97,98
        //    // hotel: 88
        //    // ticket: 1000, 10000, 1233424, 123434
        for (Map.Entry<String, List<Long>> entry : request.entrySet()) {
            String key = entry.getKey();
            List<Long> value = entry.getValue();
            Map<String, List<Long>> map = get(list, index);
            while(map.size() >= 3) {
                map = get(list, ++index);
            }
            if (value.size() <= 3) {
                map.put(key, value);
            } else {
                List<List<Long>> valueList = sliceValue(value);
                Map<String, List<Long>> tmpMap = map;
                int tmpIndex = index;
                for (int i = 0; i < valueList.size(); i++) {
                    tmpMap.put(key, valueList.get(i));
                    tmpMap = get(list, ++tmpIndex);
                }
            }
        }
        return list;
    }

    public static Map<String, List<Long>> get(List<Map<String, List<Long>>> list, int index) {
        if (list.size() == index) {
            Map<String, List<Long>> map = new HashMap<>(16);
            list.add(map);
            return map;
        }
        return list.get(index);
    }

    public static List<List<Long>> sliceValue(List<Long> value) {
        if (value.size() <= 3) {
            return Arrays.asList(value);
        }

        List<List<Long>> res = new ArrayList<>();

        for(int i = 0;i < value.size();i++) {
            int endIndex = Math.min(i + 3, value.size());
            res.add(value.subList(i, endIndex));
            i = endIndex-1;
        }
        return res;
    }