Java最常用的6个简单的计算题

public class Ball{ 
  public static void main(String[] args){ 
  int a=3,b=3,c=6,i=0; 
  for (int x=0;x<=a;x++){ 
    for (int y=0;y<=b;y++){ 
    	for (int z=0;z<=c;z++){ 
    		if (x+y+z==8){ 
      System.out.println("红球 " + x + "t白球 " + y + "t黑球 " + z ); 
      i++; 
        } 
       } 
     } 
   } 
   System.out.println("有" + i + "结果");   
  } 
}

public class Pyramid { 
public static void main(String args[]){ 
  for (int i=1; i<=32; i=i*2) { 
    for (int k=1; k<=32/i; k=k*2)System.out.print("t"); 
    for (int j=1; j<=i; j=j*2)System.out.print("t"+j); 
    for (int m=i/2; m>=1; m=m/2) System.out.print("t"+m); 
    System.out.print("n"); 
        } 
      } 
   } 

import java.util.Scanner; 

public class Date{ 
public static void main(String[] args) { 
  @SuppressWarnings("resource")//取消对input的警报 
  Scanner input=new Scanner(System.in);//声明扫描仪变量 
  System.out.println("请输入----年--月--日");//系统提示输入 
  int y = input.nextInt(); 
  int m = input.nextInt(); 
  int d = input.nextInt(); 
  if (y>=1900&&y<=2050&&m>=1&&m<=12&&d>=1&&d<=31) 
    System.out.print("日期正确"); 
  else 
    System.out.print("日期不正确"); 
  } 
} 

public class Num{
	public static void main(String[] args) {
		double sum=0;
		for(int i=1;i<=10;i++)
		   sum=sum+i/(2.0*i-1);
		System.out.println(sum);
	}
}

public class Bank { 
  public static double CBM(double money,double interest,int years){  
    for(int i=1;i<=years;i++){   
      money = money *(1+ interest);  
    } 
    return money; 
  } 
  public static void main(String[] args) { 
	  System.out.println("300000元10年后的存款金额为"+CBM(300000,0.07,20)); 
	  System.out.println("200000元20年后的存款金额为"+CBM(200000,0.06,20)); 
  } 
} 

import java.util.Scanner;

public class Circular{ 
  public static void main(String[] args) { 
    @SuppressWarnings("resource")//取消对input的警报 
    Scanner input=new Scanner(System.in);//声明扫描仪变量 
    System.out.println("请输入五边形半径");//系统提示输入 
    double r = input.nextDouble(); 
    double S; 
    S=5*(2*r*Math.sin(Math.PI/5)*(Math.pow(2*r*Math.sin(Math.PI/5),2))/(4*Math.tan(Math.PI/5))); 
    System.out.println("五边形的面积为"+S); 
  } 
}