recursion.java

一些Java的小的应用程序

/**递归的应用*/
//import java.math.*;
import java.io.*;
public class Recursion {
	//========================RECURSION========================
//--1--
public static int sum(int n){
 if(n==1) return 1;
  else return sum(n-1)+n;
}
//--2--
public static int pingfanghe(int n){
if(n==1) return 1;
else return n*n+pingfanghe(n-1);}
//--3--
public static int lifanghe(int n){
if(n==1) return 1;
else return  (int)Math.pow(n,3)+lifanghe(n-1);
}
//--4--
public static int nfanghe(int n,int m){
if(n==1) return 1;
else return (int)Math.pow(n,m)+nfanghe(n-1,m);}
//--5--
public static double cheng(int n){
if(n==1) return 1;
else return 1.0/jiecheng(n)+cheng(n-1);}
private static int jiecheng(int n){
if(n==1)return 1;
else return n*jiecheng(n-1);
}
//--6--
public static double a(int n,int k){
if(n==1) return 1;
else return 1.0/Math.pow(n,k)+a(n-1,k);
}public static void main(String args[]){
	try{
		BufferedReader input=new BufferedReader
		(new InputStreamReader(System.in));
		System.out.println("Enter two Integers!");
		int n1=Integer.parseInt(input.readLine());
		int n2=Integer.parseInt(input.readLine());
		System.out.println("The result is:");
		System.out.println();
		for(int i=1;i<n1;i++)
		System.out.print(i+"+");
		System.out.println(n1+"= "+sum(n1));
		System.out.println();
		for(int i=1;i<n2;i++)
		System.out.print(i+"+");
		System.out.println(n2+"= "+sum(n2));
		System.out.println();
		for(int i=1;i<n1;i++)
		System.out.print(i+"^2+");
		System.out.println(n1+"^2= "+pingfanghe(n1));
		System.out.println();
	    for(int i=1;i<n2;i++)
		System.out.print(i+"^2+");
		System.out.println(n2+"^2= "+pingfanghe(n2));
		System.out.println();
	    for(int i=1;i<n1;i++)
		System.out.print(i+"^3+");
		System.out.println(n1+"^3= "+lifanghe(n1));
		System.out.println();
		for(int i=1;i<n2;i++)
		System.out.print(i+"^3+");
		System.out.println(n2+"^3= "+lifanghe(n2));
		System.out.println();
		for(int i=1;i<n1;i++)
		System.out.print(i+"^"+n2+"+");
		System.out.println(n1+"^"+n2+"= "+nfanghe(n1,n2));
		System.out.println();
		for(int i=1;i<n1;i++)
		System.out.print("1/"+i+"!+");
		System.out.println("1/"+n1+"!= "+cheng(n1));
		System.out.println();
		for(int i=1;i<n2;i++)
		System.out.print("1/"+i+"!+");
		System.out.println("1/"+n2+"!= "+cheng(n2));
		System.out.println();
		for(int i=1;i<n1;i++)
		System.out.print("1/"+i+"^"+n2+"+");
		System.out.println("1/"+n1+"^"+n2+"= "+a(n1,n2));
		System.out.println();
	}catch(Exception e){}
}
}