面试编程题目（一）细菌总数计算
题目如图：
第一题：
import lombok.AllArgsConstructor;
import lombok.Data;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
/**
* @description: 细菌实体类
* @author: zhangmy
* @Version: 1.0
* @create: 2021-03-30 11:23
**/
@Data
@AllArgsConstructor
public class Bacteria {
//最大繁殖次数
private static final int MAX_BREED_NUMBER = 3;
//可繁殖时间
private static final int CAN_BREED_TIME = 20;
//繁殖间隔
private static final int BREED_CD_TIME = 30;
//存活时间
private int liveMinute;
//繁殖次数
private int breedNumber;
//距离可繁殖的倒计时
private int breedCountDown;
//当前是否可繁殖
private boolean isCanBreed;
//细菌是否死亡
private boolean isDead;
public Bacteria() {
this.liveMinute = 0;
this.breedNumber = 0;
this.isCanBreed = false;
this.breedCountDown = 20;
this.isDead = false;
}
//生长
public void grow(int minutes) {
this.liveMinute = this.liveMinute + minutes;
this.breedCountDown = this.breedCountDown - minutes;
if (this.liveMinute > 150) {
this.isDead = true;
return;
}
if (!this.isDead && this.breedCountDown == 0 && this.breedNumber < MAX_BREED_NUMBER) {
this.isCanBreed = true;
} else {
this.isCanBreed = false;
}
}
//繁殖
public List<Bacteria> breed(){
if (!this.isCanBreed) {
return Collections.emptyList();
}
//繁殖过后次数加1
this.breedNumber++;
this.breedCountDown = BREED_CD_TIME;
return Arrays.asList(new Bacteria(),new Bacteria());
}
}
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Set;
/**
* @description: 测试Main
* @author: zhangmy
* @Version: 1.0
* @create: 2021-03-30 11:59
**/
public class Main {
public static void main(String[] args) {
Bacteria bacteria1 = new Bacteria();
System.out.println(List.class.getClassLoader());
System.out.println(bacteria1.getClass().getClassLoader().getParent());
Scanner in = new Scanner(System.in);
while (true) {
System.out.println("输入时间：");
int minute = in.nextInt();
long totalStart = System.currentTimeMillis();
List<Bacteria> bacterias = new ArrayList<>();
bacterias.add(new Bacteria());
for (int i = 10; i <= minute; i+=10) {
List<Bacteria> bornBacterias = new ArrayList<>();
long start = System.currentTimeMillis();
for (int j = 0; j < bacterias.size();j++) {
Bacteria bacteria = bacterias.get(j);
bacteria.grow(10);
if (bacteria.isDead()) {
bacterias.remove(bacteria);
j--;
continue;
}
bornBacterias.addAll(bacteria.breed());
}
long end = System.currentTimeMillis();
System.out.println("遍历了" + bacterias.size() + "个！耗时：" + (end - start) + "ms");
bacterias.addAll(bornBacterias);
//System.out.println("观察时间点：" + i + "，细菌有：" + bacterias.size());
}
long totalEnd = System.currentTimeMillis();
System.out.println("总耗时：" + (totalEnd - totalStart) + "ms");
System.out.println("细菌总个数：" + bacterias.size());
}
}
}
第一题面试官给的答案是满意。
第二题：
import java.util.*;
import java.util.stream.Collectors;
/**
* @description: 数字区间
* @author: zhangmy
* @Version: 1.0
* @create: 2021-03-30 13:54
**/
public class ParseNumber {
//解析输入
public static Set<Long> parseRule(String rule) {
Set<Long> result = new HashSet<>();
String[] split = rule.split(",");
for (int i = 0; i < split.length; i++) {
if (split[i].contains("-")) {
String[] numbers = split[i].split("-");
if (numbers.length == 2) {
Long start = Long.parseLong(numbers[0]);
Long end = Long.parseLong(numbers[1]);
for (Long index = start; index < end; index++) {
result.add(index);
}
}
} else {
result.add(Long.parseLong(split[i]));
}
}
return result;
}
public static String deparseRule(Set<Long> set) {
StringBuilder result = new StringBuilder();
List<String> members = new ArrayList<>();
List<Long> list = new ArrayList<>(set).stream().sorted().collect(Collectors.toList());
for (int i = 0; i < list.size(); i++) {
StringBuilder sb = new StringBuilder();
sb.append(list.get(i));
//区间形式
if ((i + 1 < list.size()) && (list.get(i + 1) == list.get(i) + 1)) {
sb.append("-");
while ((i + 1 < list.size()) && (list.get(i + 1) == list.get(i) + 1)) {
i++;
}
//右开，需要+1
sb.append(list.get(i) + 1);
}
members.add(sb.toString());
}
for (String temp : members) {
result.append(temp).append(",");
}
//去掉最后一个逗号
String substring = result.substring(0, result.length() - 1);
return substring;
}
//判断是否是子集
public static boolean isFullContains(Set<Long> a,Set<Long> b) {
for (Long i : a) {
if (!b.contains(i)) {
return false;
}
}
return true;
}
//计算交集
public static Set<Long> calIntersection(Set<Long> a,Set<Long> b) {
Set<Long> result = new HashSet<>();
for (Long i : a) {
if (b.contains(i)) {
result.add(i);
}
}
return result;
}
//计算并集
public static Set<Long> calSet(Set<Long> a,Set<Long> b) {
a.addAll(b);
return a;
}
}
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Set;
/**
* @description: 测试Main
* @author: zhangmy
* @Version: 1.0
* @create: 2021-03-30 11:59
**/
public class Main {
public static void main(String[] args) {
//默认区间左闭右开
String as = "1,5-99999";
String bs = "2,4-99999";
long start = System.currentTimeMillis();
//判断是否包含
Set<Long> a = ParseNumber.parseRule(as);
Set<Long> b = ParseNumber.parseRule(bs);
System.out.println("是否包含：" + ParseNumber.isFullContains(a,b));
//求交集
Set<Long> intersection = ParseNumber.calIntersection(a, b);
System.out.println("交集：" + ParseNumber.deparseRule(intersection));
//求并集
Set<Long> set = ParseNumber.calSet(a, b);
System.out.println("并集：" + ParseNumber.deparseRule(set));
long end = System.currentTimeMillis();
System.out.println("消耗时间：" + (end - start) + "ms");
}
}
第二题面试官未作评价，尚未知结果如何。