等差数列计算.java

来自「一些经典的java程序适合初学者」· Java 代码 · 共 25 行

//等差数列计算
class A
{
	public int sum1(int a1,int n,int d)
	{
		int sum;
		sum=n*a1+n*(n-1)*d/2;
		return sum;
	}
	public int sum2(int a1,int an,int n)
	{
		int sum;
		sum=(a1+an)*n/2;
		return sum;
	}
}
public class Sum
{
	public static void main(String[] args)
	{
		int a1=3,n=15,d=4,an=59;
		A a=new A();
		System.out.printf("用sum1计算结果为:%d\n,用sum2计算结果为%d\n",a.sum1(3,15,4),a.sum2(3,59,15));
	}
}