java笔试

package head.first.java.prize;

import java.util.*;

public class test {
    private static final int mulriple = 5000;
    public int luckDraw(List<Prize> prizes) {
        int lastScope = 0;
        Collections.shuffle(prizes);
        Map<Integer, int[]> prizeScopes = new HashMap<Integer, int[]>();//区间
        Map<Integer, Integer> prizeQuantity = new HashMap<Integer, Integer>();//数量
        for (Prize prize : prizes) {
            int prizeId = prize.getPrizeId();
            int currentScope = lastScope + (int)(prize.getProbability()*mulriple);//区间划分
            prizeScopes.put(prizeId, new int[] { lastScope + 1, currentScope });//奖品中奖的区间
            prizeQuantity.put(prizeId, prize.getQuantity());//有多少奖品
            lastScope = currentScope;
        }
        int luckyNumber = new Random().nextInt(mulriple);
        int luckyPrizeId = 0;
        if ((null != prizeScopes) && !prizeScopes.isEmpty()) {
            Set<Map.Entry<Integer, int[]>> entrySets = prizeScopes.entrySet();
            for (Map.Entry<Integer, int[]> m : entrySets) {
                int key = m.getKey();
                if (luckyNumber >= m.getValue()[0] && luckyNumber <= m.getValue()[1] && prizeQuantity.get(key) > 0) {
                    luckyPrizeId = key;
                    break;
                }
            }
        }
        if (luckyPrizeId > 0) {
            int i = prizeQuantity.get(luckyPrizeId);
            i--;
            prizeQuantity.put(luckyPrizeId,i);
        }
        return luckyPrizeId;
    }
    public void findNumber() {
        String[] array={"1","5","33","7","8","27","5","90","2","6","25"};
        int[] arr = new int[array.length];
        int max = 0;
        int min = 0;
        for(int x=0; x<arr.length; x++){
            arr[x]=Integer.parseInt(array[x]);
            if(arr[x]>arr[max]){
                max = x;
            }
            if(arr[x]<arr[min]){
                min = x;
            }
        }
        System.out.println(arr[max]*arr[min]); ;
    }
    public static boolean checkEqual(Integer num) {
        return num==100;
    }
    public Map<Integer,Integer> findAndReturn(List<Integer> list){
        Map<Integer,Integer> map = new HashMap<Integer,Integer>();
        int i=0,j=0,z=0;
        for(;i<list.size();i++){
            char lastChar = String.valueOf(list.get(i)).charAt(String.valueOf(list.get(i)).length()-1);
            if((lastChar=='5'||lastChar=='0')&&!checkEqual(list.get(i))){
                j++;
            }
            if((lastChar=='0'||lastChar=='2'||lastChar=='4'||lastChar=='6'||lastChar=='8')&&!checkEqual(list.get(i))){
                z++;
            }
        }
        map.put(2,z);
        map.put(5,j);
        return map;
    }
    public static void main(String[] args) {
        List<Prize> prizes = new ArrayList<Prize>();
        Prize prize1 = new Prize();
        prize1.setPrizeId(1);//id
        prize1.setProbability(0.0006);//概率3/5000
        prize1.setQuantity(3);//数量
        prizes.add(prize1);
        Prize prize2 = new Prize();
        prize2.setPrizeId(2);//id
        prize2.setProbability(0.02);//概率100/5000
        prize2.setQuantity(100);//数量
        prizes.add(prize2);
        Prize prize3 = new Prize();
        prize3.setPrizeId(3);//id
        prize3.setProbability(0.01);//概率50/5000
        prize3.setQuantity(50);//数量
        prizes.add(prize3);
        int prizeOne = 0;
        int prizeTwo = 0;
        int prizeThree = 0;
        test test =new test();
        for (int i = 0; i < 1000; i++) {
            int prizeId = test.luckDraw(prizes);
            switch (prizeId) {
                case 1:
                    prizeOne++;
                    break;
                case 2:
                    prizeTwo++;
                    break;
                case 3:
                    prizeThree++;
                    break;
            }
        }
        System.out.println("prize1中奖次数" + prizeOne);
        System.out.println("prize2中奖次数" + prizeTwo);
        System.out.println("prize3中奖次数" + prizeThree);
        test.findNumber();
        List<Integer> list = new ArrayList<Integer>();
        list.add(1);
        list.add(2);
        list.add(5);
        list.add(10);
        list.add(20);
        list.add(25);
        list.add(27);
        list.add(100);
        list.add(99);
        System.out.println(test.findAndReturn(list).toString());
    }
}

package head.first.java.prize;

public class Prize {
    private Integer prizeId;//奖品id
    private Double probability;//中奖概率
    private Integer quantity;//奖品数量

    public Integer getPrizeId() {
        return prizeId;
    }

    public void setPrizeId(Integer prizeId) {
        this.prizeId = prizeId;
    }

    public Double getProbability() {
        return probability;
    }

    public void setProbability(Double probability) {
        this.probability = probability;
    }

    public Integer getQuantity() {
        return quantity;
    }

    public void setQuantity(Integer quantity) {
        this.quantity = quantity;
    }
}

 

package com.yz;
/***
 * 所有实现均基于JDK，不可使用第三方中间件
* 1.实现下方的抽奖方法(luckdraw)，提供5000次抽奖机会，奖品有一等奖3个，二等奖 100个，三等奖50个，各个奖品需在5000次抽奖中尽量平均分布，但不可有规律被抽中
* 2.实现下方的数字查找方法，查找最大数和最小数，并得出它们的乘积（不可使用集合工具类）
* 3.实现下方的查找方法（findAndReturn）供他人调用，传入参数为不可预知的List，分别查找List中2的倍数，5的倍数出现的次数，调用checkEqual方法判断如果返回true就不计入次数，最后返回结果集，此方法有性能要求。
 */
public class Demo {
        
    /***
     * 检查是否等于100
     *@param num 比较值
     *@return 相等返回true 否则false
     */
    public static boolean checkEqual(Integer num) {
            return num==100;
    }
    
    public void luckDraw() {
        // do something
    }
    
    public void findNumber() {
        String[] array={"1","5","33","7","8","27","5","90","2","6","25"};
        // do something
    }

    public Map<Integer,Integer> findAndReturn(List<Integer> list){

    }
    
}