【笔试题】素数天购买设备

题目描述

题解

自己尝试解了一下，不知道对不对

import java.util.*;

public class Main {
    public static Map<Integer,Integer> map = new TreeMap<Integer,Integer>();
    public static List<Integer> primeList = new ArrayList<>();
    public static int res = 0;

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();

        int mapIndex = 1;
        while (in.hasNextInt()) {
            map.put(mapIndex++, in.nextInt());
        }
        List<Map.Entry<Integer, Integer>> list = new ArrayList<Map.Entry<Integer, Integer>>(map.entrySet());

        // 素数生成
        primeCreate();

        // 用户的购买位置
        int buyTime = 0;
        for (int primeDay: primeList) {
            if (primeDay > list.size()) break;

            // 子列表
            List<Map.Entry<Integer, Integer>> templist = new ArrayList<>();
            for (int i = 0; i < primeDay; i++) {
                templist.add(list.get(i));
            }
            // map按照value排序
            Collections.sort(templist, new Comparator<Map.Entry<Integer,Integer>>() {
                public int compare(Map.Entry<Integer, Integer> o1, Map.Entry<Integer, Integer> o2) {
                    return o1.getValue().compareTo(o2.getValue());
                }
            });

//            for (Map.Entry<Integer, Integer> e: templist) {
//                System.out.print(e.getKey()+":"+e.getValue() +  " ");
//            }
//            System.out.println();
//
            res += templist.get(buyTime++).getValue();
        }

        System.out.println(res);
    }

    // 素数生成
    public static void primeCreate() {
        int i = 2;
        int count = 0;
        while (count <= map.size()) {
            if (isPrime(i)) {
                count++;
                primeList.add(i);
            }
            i++;
        }
    }

    public static boolean isPrime(int n) {
        if (n == 2) {
            return true;
        } else if (n < 2) {
            return false;
        }
        double max = Math.sqrt(n) + 1;
        for (int i = 2; i < max; i++) {
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }
}