1. 利用循环打印如下图形
*****
****
***
**
*
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
int i = 5;
while (i >= 0) {
for (int j = i; j > 0; j--)
System.out.print("*");
System.out.println();
i--;
}
}
}
2.利用循环打印如下图形
*
**
***
****
*****
****
***
**
*
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
int i = 1;
while (i <= 5) {
for (int j = 0; j < i; j++)
System.out.print("*");
System.out.println();
i++;
}
i = 4;
while (i >= 0) {
for (int j = i; j > 0; j--)
System.out.print("*");
System.out.println();
i--;
}
}
}
3.利用循环打印如下图形
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
int k = 5;
for (int i = 1; i <= k; i++) {
for (int m = k - i; m > 0; m--)
System.out.print(" ");
for (int n = i; n > 0; n--)
System.out.print("* ");
System.out.println();
}
for (int i = k - 1; i >= 0; i--) {
for (int m = 1; m <= k - i; m++)
System.out.print(" ");
for (int n = i; n > 0; n--)
System.out.print("* ");
System.out.println();
}
}
}
4.输出所有的水仙花数，所谓水仙花数是指一个3位数，其各个位上数字立方和等于其本身。
例如： 153 = 1*1*1 + 3*3*3 + 5*5*5
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
for (int i = 1; i <= 9; i++)
for (int j = 0; j <= 9; j++)
for (int k = 0; k <= 9; k++) {
if (i * i * i + j * j * j + k * k * k == (i * 100 + j * 10 + k))
System.out.println(i * 100 + j * 10 + k);
}
}
}
5.
问题一：
从键盘读入个数为10个的整数，并判断读入的正数和负数的个数。
问题二：
从键盘读入个数不确定的整数，并判断读入的正数和负数的个数，输入为0时结束程序。
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc=new Scanner(System.in);
funCount(sc.nextInt());
sc.close();
}
private static void funCount(int type) {
Scanner sc=new Scanner(System.in);
int i=0,plus=0,minus=0;
if(type==1){
System.out.println("输入10个数");
do{
if(sc.nextInt()>=0)plus++;
else
minus++;
i++;
}while(i<10);
System.out.println("正数的个数为："+plus+"负数的个数为："+minus);
}
else{
System.out.println("输入任意个数字，以0结束");
int ip;
while((ip=sc.nextInt())!=0){
if(ip>0)plus++;
else
minus++;
}
System.out.println("正数的个数为："+plus+"负数的个数为："+minus);
}
sc.close();
}
}
6.100以内的所有质数
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
for (int i = 2; i <= 100; i++) {
int sum = 0;
if (i == 2 || i == 3)
System.out.println(i);
else {
for (int j = 2; j < i; j++) {
if (i % j == 0) {
sum++;
break;
}
}
if (sum == 0)
System.out.println(i);
}
}
}
}
7.一个数如果恰好等于它的因子之和，这个数就称为"完数"。（因子：除去这个数本身正的约数）
例如6=1＋2＋3.编程 找出1000以内的所有完数
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
for (int i = 1; i <= 1000; i++) {
int sum = 0;
for (int j = 1; j <= i / 2; j++) {
if (i % j == 0)
sum += j;
}
if (sum == i)
System.out.println(i);
}
}
}
【以下可能用到数组，把排序的数可以提前初始化到一个int数组当中，如
int[] dataSort = new int[]{9, -16, 21, 23, -30, -49, 21, 30, 30};
访问其中每个数就利用下标进行，下标从0开始的，如 取dataSort[2]，得到的值就是 21.
】
以下是把数据结构当中所学的基本排序算法都一一实现一下。
8.直接插入排序 10. 直接选择排序 11. 冒泡排序 12. Shell排序 13. 快速排序
第9-13题的排序每个同学们必做，14-17同学们根据自己的能力选做
【14. 折半插入排序 15. 堆排序 16. 归并排序 17.基数排序 】
注：这里采用随机数组，取值范围是在-100到100之间，每个排序方法定义一个类，保证使用方式上基本一致，后面三种排序方法写起来麻烦懒得写了。
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
int dataSort[] = new int[10];
for (int i = 0; i < dataSort.length; i++) {
dataSort[i] = (int) (Math.random() * 200) - 100;
}
int dataBackup[] = dataSort;// 备份数组保证每次排序的初始内容一样
dataSort = dataBackup;
StraightInsertionSort sis = new StraightInsertionSort(dataSort);// 直接插入排序
printData(sis.TAG, sis.data);
dataSort = dataBackup;
StraightSelectSort sss = new StraightSelectSort(dataSort);// 直接选择排序
printData(sss.TAG, sss.data);
dataSort = dataBackup;
BubbleSort bbs = new BubbleSort(dataSort);// 冒泡排序
printData(bbs.TAG, bbs.data);
dataSort = dataBackup;
ShellSort ss = new ShellSort(dataSort);// Shell排序
printData(ss.TAG, ss.data);
dataSort = dataBackup;
QuickSort qs = new QuickSort(dataSort);
printData(qs.TAG, qs.data);
dataSort = dataBackup;
BinarySort bs = new BinarySort(dataSort);// 折半插入排序
printData(bs.TAG, bs.data);
}
private static void printData(String a, int[] d) {
// TODO Auto-generated method stub
System.out.printf("%-15s\t", new Object[] { a });
System.out.print("-->\t");
for (int i = 0; i < d.length; i++) {
System.out.print(d[i] + "\t");
}
System.out.println();
}
}
public class StraightInsertionSort {
String TAG="直接插入排序";
int data[];
public StraightInsertionSort(int data[]){
this.data=data;
sort(data);
}
private void sort(int[] d) {
// TODO Auto-generated method stub
int temp;// 存放最小元素
for (int i = 1; i < d.length; i++) {
int j = i - 1;
temp = d[i];
while (temp < d[j]) {
d[j+1] = d[j];
j--;
if (j < 0)
break;
}
d[j + 1] = temp;
}
}
}
public class StraightSelectSort {
String TAG="直接选择排序";
int data[];
public StraightSelectSort(int data[]){
this.data=data;
sort(data);
}
private void sort(int[] d) {
// TODO Auto-generated method stub
int temp;// 临时变量
for (int i = 1; i < d.length; i++) {
int k = i;// 记录最小元素位置
for (int j = i + 1; j < d.length; j++) {
if (d[j] < d[k])
k = j;
if (k != i) {
temp = d[k];
d[k] = d[i];
d[i] = temp;
}
}
}
}
}
public class BubbleSort {
String TAG = "冒泡排序";
int data[];
public BubbleSort(int data[]) {
this.data = data;
sort(data);
}
private void sort(int[] d) {
// TODO Auto-generated method stub
boolean hasSort = true;// 判断是否进行排序了的标识
int i = 0;
while (i < d.length && hasSort == true) {
hasSort = false;
for (int j = 0; j < d.length - 1; j++) {
if (d[j + 1] < d[j]) {
int temp = d[j];
d[j] = d[j + 1];
d[j + 1] = temp;
hasSort = true;
}
}
i++;
}
}
}
public class ShellSort {
String TAG="Shell排序";
int data[];
public ShellSort(int data[]){
this.data=data;
sort(data);
}
private void sort(int[] d) {
// TODO Auto-generated method stub
for (int t = d.length / 2; t >= 1; t = t / 2) {
for (int i = t ; i < d.length; i++) {
int temp = d[i];
int j;
for (j = i - t; j >= 0 && temp < d[j]; j = j - t) {
d[j + t] = d[j];
}
d[j + t] = temp;
}
}
}
}
public class QuickSort {
String TAG="快速排序";
int data[];
public QuickSort(int data[]){
this.data=data;
sort(data,0,data.length-1);
}
private void sort(int[] d, int left, int right) {
// TODO Auto-generated method stub
if(left>=right)return;
int temp=0;
temp=d[left];
int l= left, r = right;
while (l < r) {
while (l<r&&d[r] > temp)
r--;
if(l<r)d[l++]=d[r];
while (l<r&&d[l] < temp)
l++;
if(l<r)d[r--]=d[l];
}
d[l]=temp;
sort(d, left, l-1);
sort(d, l+1, right);
}
}
public class BinarySort {
String TAG = "折半插入排序";
int data[];
public BinarySort(int data[]) {
this.data = data;
sort(data);
}
private void sort(int[] d) {
// TODO Auto-generated method stub
for (int i = 1; i < d.length; i++) {
int temp = d[i];
int left = 0, right = i - 1;
while (left <= right) {
int mid = (left + right) / 2;
if (d[i] < d[mid])
right = mid - 1;
else
left = mid + 1;
}
for (int j = i - 1; j >= left; j--)
d[j + 1] = d[j];
d[left] = temp;
}
}
}
时间： 2024-08-22 03:26:42