java课题--day1基础回顾
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2022-05-04 18:10:48
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大课题Day01–回顾java基础
输入年月日,判断是哪一天
import java.util.Scanner;
/**
* @author Shangkejie
* @Class BigData182
* @date 2019/12/9 - 11:49
*/
public class demo01 {
public static void main(String[] args) {
//输入年月日,判断是哪一天
System.out.println("输入年月日,回车隔开");
Scanner input=new Scanner(System.in);
int year=input.nextInt();
int month=input.nextInt();
int date=input.nextInt();
System.out.println("你输入的日期是"+year+"\t"+month+"\t"+date);
//判断是不是闰年
if((year%4==0&&year%100!=0) || year % 400==0) {
//闰年
System.out.println("今年是润年");
switch(month) {
case 1:
System.out.println(date);
break;
case 2:
System.out.println(30+date);
break;
case 3:
System.out.println(59+date);
break;
case 4:
System.out.println(90+date);
break;
case 5:
System.out.println(120+date);
break;
case 6:
System.out.println(151+date);
break;
case 7:
System.out.println(181+date);
break;
case 8:
System.out.println(212+date);
break;
case 9:
System.out.println(243+date);
break;
case 10:
System.out.println(273+date);
break;
case 11:
System.out.println(304+date);
break;
case 12:
System.out.println(335+date);
break;
}
}else {
//平年
System.out.println("今年是平年");
switch (month) {
case 1:
System.out.println(date);
break;
case 2:
System.out.println(30 + date);
break;
case 3:
System.out.println(58 + date);
break;
case 4:
System.out.println(89 + date);
break;
case 5:
System.out.println(119 + date);
break;
case 6:
System.out.println(150 + date);
break;
case 7:
System.out.println(180 + date);
break;
case 8:
System.out.println(211 + date);
break;
case 9:
System.out.println(242 + date);
break;
case 10:
System.out.println(272 + date);
break;
case 11:
System.out.println(303 + date);
break;
case 12:
System.out.println(334 + date);
break;
}
}
}
}
九九口诀
/**
* @author Shangkejie
* @Class BigData182
* @date 2019/12/9 - 14:28
*/
public class demo02 {
//九九口诀
//控制行数
public static void main(String[] args) {
for (int i = 1; i <= 9; i++) {
//控制列数
for (int j = 1; j <= i; j++) {
System.out.print(i+"*"+j+"="+i*j+"\t");
}
System.out.println(" ");
}
}
}
求某个数的阶乘和
/**
* @author Shangkejie
* @Class BigData182
* @date 2019/12/9 - 15:19
*/
public class demo03 {
// 求某个数的阶乘和
public static void main(String[] args) {
int sum=0;
for (int i=1;i<=10;i++){
sum+=jiecheng(i);
System.out.println(i+"的阶层和是"+sum);
}
}
public static int jiecheng(int num) {
int re=1;
for (int i=1;i<num+1;i++){
re*=i;
System.out.println(i+"的阶乘是"+re);
}
return re;
}
}
1到100的质数和
/**
* @author Shangkejie
* @Class BigData182
* @date 2019/12/9 - 15:31
*/
public class demo04 {
//1到100的质数和
public static void main(String[] args) {
int sum=0;
for (int i=1;i<=100;i++){
//100到1质数的和(不包括1)
sum+=zhishu(i);
}
System.out.println("质数的和为"+(sum-1));
}
//从2开始判断质数
public static int zhishu(int num){
boolean flag=true;
for (int j=2;j<=Math.sqrt(num);j++){
if (num%j==0) {
System.out.println(num+"不是质数");
flag=false;
break;
}
}
//不是质数
if (flag==false){
return 0;
}else{//是质数
return num;
}
}
}
数组相关
import java.util.Arrays;
/**
* @author Shangkejie
* @Class BigData182
* @date 2019/12/9 - 16:34
*/
public class demo05 {
//求数组中的最大值
public static void main(String[] args) {
int []arg={12,34,-23,18,90};
int max=arg[0];
int min=arg[0];
Arrays.sort(arg);//调用java的排序
max=arg[arg.length-1];
min=arg[0];
System.out.println("最大值是"+max);
System.out.println("最小值是"+min);
System.out.println("从小到大排序后的数组:");
for (int i=0;i<arg.length;i++){
System.out.print(arg[i]+" ");
}
//手写求最大值
int tem=0;
for (int i=0;i<arg.length-1;i++){
if (arg[i]>arg[i+1]){
tem=arg[i];
arg[i]=arg[i+1];
arg[i+1]=tem;
}
}
System.out.println("\n max is "+arg[arg.length-1]);
for (int i=0;i<arg.length-1;i++){
if (arg[i]<arg[i+1]){//求最小值
tem=arg[i];
arg[i]=arg[i+1];
arg[i+1]=tem;
}
}
System.out.println("min is "+arg[arg.length-1]);
}
}
冒泡排序
/**
* @author Shangkejie
* @Class BigData182
* @date 2019/12/9 - 16:53
*/
public class demo07 {
//冒泡排序,从小到大
public static void main(String[] args) {
int[] arr={12,34,56,78,99,28,16};
//从第一个开始
//外层循环次数1到6
for (int i=1;i<arr.length;i++){
//内层循环次数6到1
for (int j=0;j<arr.length-i;j++) {
int m = 0;//临时变量
if (arr[j]> arr[j+1]) {//大的沉底
m = arr[i];
arr[j] = arr[j+ 1];
arr[j+1] = m;
}
}
}
for (int i=0;i<arr.length;i++){
System.out.print(arr[i]+" ");
}
}
}
杨辉三角
/**
* @author Shangkejie
* @Class BigData182
* @date 2019/12/9 - 17:33
*/
public class demo08 {
//杨辉三角
public static void main(String[] args) {
//设置行数
int hang=10;
//二维数组存放杨辉三角
int[][] yanghui = new int [hang][];//10行N列
//控制列数
for (int i=0;i<yanghui.length;i++){
yanghui[i]=new int [i+1];//列数等于行数
}
//开始计算杨辉三角
for (int i=0;i<yanghui.length;i++){//控制行数
for (int j=0;j<yanghui[i].length;j++){//列数等于行数
yanghui[i][0]=yanghui[i][i]=1;//对角线和第一列都为1
if (i>0 && j>0 && j<i){
yanghui[i][j]=yanghui[i-1][j]+yanghui[i-1][j-1];//其余的元素等于上一行的数+上一行左边的数
}
}
}
//输出
for (int i=0;i<yanghui.length;i++) {
for (int b=5;b<yanghui.length;b++) {
System.out.print(" ");
}
for (int j = 0; j < yanghui[i].length; j++) {
System.out.print(yanghui[i][j]+" ");
}
System.out.println(" ");
}
}
}
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