《JAVASE系列》牛客网java入门题集题解第一篇
前言
本章讲解牛客网的java初级编程入门的前十五道题目。作为初学者，无论是已经学习了c语言去适应java语言的编程入门者，还是将java作为入门语言的新手，都适合将这个系列刷完。
刷题链接：编程语法练习-Java初级语法_牛客网 (nowcoder.com)
JAVA1 类型转换
题目：
题解：
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
double d = scanner.nextDouble();
System.out.println(Main.typeConversion(d));
}
public static int typeConversion(double d){
return (int) d;
JAVA2 简单运算
题目
题解：
public static void incloud(int a,int b){
int c = a + b;
int d = a - b;
int e = a * b;
int f = a / b;
int g = a % b;
System.out.println(c+" "+d+" "+e+" "+f+" "+g+" ");
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
int b = scanner.nextInt();
scanner.close();
if(a>b){
incloud(a,b);
}
else{
incloud(b,a);
}
}
JAVA3 四舍五入
题目
题解：
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
double d= scanner.nextDouble();
int b = (int)Math.round(d);
System.out.println(b);
}
}
JAVA4 交换变量
题目
题解：
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
int b = scanner.nextInt();
a = a ^ b;
b = a ^ b;
a = a ^ b;
System.out.println(a+" "+b);
}
JAVA5 计算商场折扣
题目
题解
public static void main(String[] args) {
Scanner console = new Scanner(System.in);
int price = console.nextInt();
int cost = 0;
//write your code here......
if(price>=100&&price<500){
cost = (int)(price * 0.9);
}
else if (price>=500&&price<2000) {
cost = (int)(price * 0.8);
}
else if(price>=2000&&price<5000){
cost = (int)(price * 0.7);
}
else if(price>=5000)
{
cost = (int)(price * 0.6);
}
else{
cost = price;
}
System.out.println(cost);
}
JAVA6 判断体重指数
题目：
题解
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
double height = scanner.nextDouble();
double weight = scanner.nextDouble();
//write your code here......
double index = weight / (height*height);
if(index<18.5){
System.out.println("偏瘦");
}
else if(index>=18.5&&index<20.9) {
System.out.println("苗条");
}
else if(index>=20.9&&index<24.9) {
System.out.println("适中");
}
else{
System.out.println("偏胖");
}
}
JAVA7 判断学生成绩等级
题目：
题解
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
double height = scanner.nextDouble();
double weight = scanner.nextDouble();
//write your code here......
double index = weight / (height*height);
if(index<18.5){
System.out.println("偏瘦");
}
else if(index>=18.5&&index<20.9) {
System.out.println("苗条");
}
else if(index>=20.9&&index<24.9) {
System.out.println("适中");
}
else{
System.out.println("偏胖");
}
}
JAVA8 邮箱验证
题目
题解：
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String str = scanner.next();
String emailMatcher="[a-zA-Z0-9]+@[a-zA-Z0-9]+\\.[a-zA-Z0-9]+";
System.out.println(str.matches(emailMatcher)?"邮箱格式合法":"邮箱格式不合法");
提供该方法的学习文档：
JAVA9 数列求和
题目
题解：
public static void main(String[] args) {
//write your code here........
long a = 9;
int i = 0;
long sum = 0;
for(i=0;i<10;i++){
sum += a;
a = a*10 + 9;
}
System.out.println(sum);
}
JAVA10 统计输入正数个数
题目
题解：
public static void main(String[] args) {
int count = 0;
Scanner scanner = new Scanner(System.in);
//write your code here......
while(true){
int num = scanner.nextInt();
if(num>0){
count ++;
}
else{
break;
}
}
System.out.println(count);
}
JAVA11 求最小公倍数
题目
题解：
public static int getCM(int m, int n){
//write your code here......
int i= 0;
for(i=m;i<=m*n;i++){
if(i%m==0&&i%n==0){
break;
}
}
return i;
}
JAVA12 小球走过路程计算
题目
题解：
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);
float h=scanner.nextFloat();
int n =scanner.nextInt();
//write your code here......
double sum = h;
while(n>0){
h = h / 2;
sum += h*2;
n--;
}
sum -= h*2;
System.out.println(String.format("%.3f", h)+" "+String.format("%.3f", sum));
}
JAVA13 求平均数
题目
题解：
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
//write your code here......
int sum = 0;
int n = 0;
while(true){
int num = scan.nextInt();
if(num>=0){
sum+=num;
n++;
}
else{
break;
}
}
double avg = (double)sum/n;
System.out.println(String.format("%.2f",avg));
JAVA14 判断质数
题目
题解：
public static void main(String[] args) {
Main main = new Main();
Scanner scan = new Scanner(System.in);
int number = scan.nextInt();
System.out.println(main.isPrimeNumber(number));
}
public Boolean isPrimeNumber(int number) {
//write your code here......
int i = 0;
for(i=2;i<number-1;i++){
if(number%i==0){
return false;
}
}
return true;
}
JAVA15 计算整数位数
题目
题解：
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int num = scan.nextInt();
scan.close();
//write code here......
int n = 0;
int i = 0;
for(i=0;;i++){
if(num>0){
n++;
num = num/10;
}
else{
break;
}
}
System.out.println(n);
}
总结
这15道题主要涉及java语法的基本数据类型，运算符，分支，循环
其中较为值得理解的是 异或的计算技巧，matches 方法的使用，如何做到循环输入。
感谢阅读！
与君共勉！
