1、計算n的階乘
import java.util.Scanner;
public class jie {
public static void main(String[] args) {
int w;
System.out.print("請輸入一個整數:");
Scanner sc = new Scanner(System.in); //開啓監聽鍵盤動作
w=sc.nextInt(); //捕獲鍵盤輸入的數
System.out.println(w+"的階乘爲:"+cheng(w));
}
public static int cheng(int n) {
int sum=1;
for(int i=n;i>0;i--) {
sum*=i;
}
return sum;
}
}
2、獲取n以內的所有素數
import java.util.Scanner;
public class sushu {
public static void main(String[] args) {
int l,count=0;
System.out.print("請輸入一個整數:");
Scanner sc = new Scanner(System.in);
l=sc.nextInt();
for(int j=2;j<=l;j++) {
if(su(j)==1) {
System.out.printf("%6d",j);
count++;
if(count%10==0) { //10個數爲一行
System.out.print("\n");
}
}
}
System.out.println("\n");
}
public static int su(int n) {
for(int i=2;i<n;i++) {
if(n%i==0) {
return 0;
}
}
return 1;
}
}
3、計算數組的平均值
public class avg {
public static double ave(int[] s) {
int sum=0;
int length=s.length;
for(int i=0;i<length;i++) {
sum+=s[i];
}
return sum*1.0/length;
}
public static void main(String[] args) {
int[] w= {12,23,34,45,56,67,78,61};
double h = ave(w);
System.out.println("平均數爲:"+h);
}
}
4、計算數組的最大值,最小值,和以及平均值
public class Helloworld {
public static void main(String[] args) {
int max,min,sum=0;
double avg = 0;
int array[]= {12,23,34,45,56,67,78,89,90,100};
max=min=array[0];
for(int i=0;i<array.length;i++) {
sum+=array[i];
avg=sum*1.0/array.length;
if(array[i]>max)
max=array[i];
if(array[i]<min)
min=array[i];
}
System.out.println("max = "+max);
System.out.println("min = "+min);
System.out.println("sum = "+sum);
System.out.println("avg = "+avg);
}
}
5、打印出乘法口訣表
public class chengkou {
public static void main(String[] args) {
for(int i=1,j=1;j<=9;i++){
System.out.print(i+"*"+j+"="+i*j+" ");
if(i==j) {
i=0;
j++;
System.out.println();
}
}
}
}
6、求一個數的最大公約數
import java.util.List;
public class yue {
public static void main(String[] args) {
int myue;
yue y = new yue();
myue=y.maxCommonDivisor(4,6);
System.out.println("最大公約數爲:"+myue);
}
public static int maxCommonDivisor(int one, int two) {
int max = one * two;
int min = one > two ? one : two;
for (int i = min; i < max; i++) {
if (i % one == 0 && i % two == 0) {
return i;
}
}
return max;
}
}
7、猴子喫桃問題
猴子第一天摘下若干個桃子,當即吃了一半,還不癮,又多吃了一個 第二天早上又將剩下的桃子喫掉一半,又多吃了一個。以後每天早上都吃了前一天剩下 的一半零一個。到第10天早上想再喫時,見只剩下一個桃子了。求第一天共摘了多少。
public class monkey {
public static void main(String[] args) {
monkey mon = new monkey();
int sum=mon.monkeyEatPeach();
System.out.println("第一天摘的桃子總數爲:"+sum);
}
public int monkeyEatPeach() {
int sum = 1;
for (int i = 1; i < 10; i++) {
sum = (sum + 1) * 2;
}
return sum;
}
}
8、隨機生成幾個數
public class pratice {
public static void main(String[] args) {
int count=0;
Random random = new Random();
System.out.println("產生的隨機數爲:");
for(int i=1;i<40;i++) {
int ran=random.nextInt(100);
count++;
if(count%10==0) {
System.out.print("\n");
}
System.out.print(ran+" ");
}
}
}