Java的一些简单示例（1）

1、求两个正整数的最大公约数和最小公倍数

import java.util.Scanner;

public class Test {

    public static void main(String[] args) {

        Scanner s = new Scanner(System.in);
        System.out.println("please input an integer!");
        int max = s.nextInt();
        int sml = s.nextInt();
        int temp1,temp2;
        temp1 = max;
        temp2 = sml;
        int temp;
        int f;
        while(temp2 != 0){
            temp = temp1%temp2;
            temp1 = temp2;
            temp2 = temp;
        }
        System.out.println("最大公约数是："+ temp1);
        f = (max * sml)/temp1;
        System.out.println("最小公倍数是："+ f);
    }
}

2、求100到200之间的所有素数

public class Test {

    public static void main(String[] args) {

        for(int i=101;i<=200;i++){
            boolean b = false;
            for(int k=2;k<=Math.sqrt(i);k++){
                if(i%k == 0){
                    b = true;
                    break;
                }
            }
            if(b == false){
                System.out.println(i);
            }
        }
    }
}

3、分解质因子

import java.util.Scanner;

class Test{

    public static void main(String args[]){
        Scanner s = new Scanner(System.in);
        System.out.println("please input an integer!");
        int num = s.nextInt();
        int k = 2;

        while(k <= num){
            if(num == k){
                System.out.print(k);
                break;
            }else if(num % k == 0){
                System.out.print(k+"*");
                num = num/k;
            }else{
                k++;
            }
        }
    }
}

4、输入一行字符，分别统计出其中英文字母、空格、数字和其他字符的个数

import java.util.Scanner;

public class Test {

    public static void main(String args[]){
        Scanner s = new Scanner(System.in);
        System.out.println("please input a string!");
        String ss = s.nextLine();
        char c[] = null;
        int digital = 0;
        int character = 0;
        int black = 0;
        int other = 0;
        c = ss.toCharArray();
        for(int i=0;i<c.length;i++){
            if(c[i]<='9' && c[i]>='0'){
                digital++;
            }else if(c[i]<='z' && c[i]>='a' || c[i]<='Z' && c[i]>='A'){
                character++;
            }else if(c[i] == ' '){
                black++;
            }else{
                other++;
            }
        }
        System.out.println("digital:"+digital);
        System.out.println("character:"+character);
        System.out.println("black:"+black);
        System.out.println("other:"+other);
    }
}

5、（1）杨辉三角

public class Test {

    public static void main(String args[]){

        int array[][] = new int[10][10];
        for(int i=0;i<10;i++){
            for(int j=0;j<=i;j++){
                if(j==0 || j==i){
                    array[i][j] = 1;
                }else{
                    array[i][j] = array[i-1][j-1] + array[i-1][j];
                }
            }
        }
        for(int i=0;i<10;i++){
            for(int k=0;k<10-i;k++){
                System.out.print(" ");
            }
            for(int j=0;j<=i;j++){
                System.out.print(array[i][j]+" ");
            }
            System.out.println();
        }
    }
}

（2）用c语言实现杨辉三角

#include <stdio.h>

int main(){
    int array[10][10] = {0};
    for(int i=0;i<10;i++){
        array[i][0] = 1;
    }
    for(int k=1;k<10;k++){
        for(int j=1;j<=k;j++){
            array[k][j] = array[k-1][j-1] + array[k-1][j]; 
        }
    }
    for(int m=0;m<10;m++){
        for(int k=0;k<(10-m);k++){
            printf(" ");
        }
        for(int n=0;n<=m;n++){
            printf("%5d",array[m][n]);
        }
        printf("\n");
    }
    return 0;
}

（3）用c语言实现杨辉三角

#include <stdio.h>

int main(){
    int array[10][10];
    for(int i=0;i<10;i++){
        for(int j=0;j<=i;j++){
            if(j == 0 || j == i){
                array[i][j] = 1;
            }else{
                array[i][j] = array[i-1][j-1] + array[i-1][j];
            }
        }
    }

    for(int m=0;m<10;m++){
        for(int k=0;k<(10-m);k++){
            printf(" ");
        }
        for(int n=0;n<=m;n++){
            printf("%5d",array[m][n]);
        }
        printf("\n");
    }
    return 0;
}

6、找出1000以内的所有完数

class Test{

    public static void main(String args[]){
        for(int i=1;i<1000;i++){
            int sum = 0;
            for(int j=1;j<=i/2;j++){
                if(i%j == 0){
                    sum = sum + j;
                }
            }
            if(sum == i){
                System.out.println(i+" ");
            }
        }
    }
}

7、一球从100米高度自由落下，每次落地后反跳回原高度的一半；再落下，求它在第10次落地时，共经过多少米？第10次反弹多高？

public class Test {

    public static void main(String[] args) {

        double sum = 100;
        double height = 100;
        for(int i=1;i<=9;i++){
            height = height/2;
            sum = sum + 2*height;
        }
        System.out.println(height/2);
        System.out.println(sum);
    }
}

8、输入某年某月某日，判断这一天是这一年的第几天？

import java.util.Scanner;

public class Test {

    public static void main(String[] args) {

        int year;
        int month;
        int day;
        int days = 0;
        int sum = 0;
        Scanner s = new Scanner(System.in);
        System.out.println("请输入年！");
        year = s.nextInt();
        System.out.println("请输入月！");
        month = s.nextInt();
        System.out.println("请输入日！");
        day = s.nextInt();

        if(year<=0 || month<=0 || month>12 || day<=0 || day>31){
            System.out.println("error!");
            System.exit(-1);
        }

        for(int i=1;i<month;i++){
            if(i == 1 || i == 3 || i == 5 || i == 7 || i == 8 || i == 10 || i == 12){
                days = 31;
            }
            if(i == 4 || i == 6 || i == 9){
                days = 30;
            }
            if(i == 2 && ((year%400 == 0) || (year%100 != 0 && year%4 == 0))){
                days = 29;
            }
            if(i == 2 && !((year%400 == 0) || (year%100 != 0 && year%4 == 0))){
                days = 28;
            }
            sum = sum + days;
        }
        sum = sum + day;
        System.out.println(year + "-" + month + "-" + day + "是这年的第" + (sum) + "天。");
    }
}