Question

Java 阶乘的倒数求和老是出问题，求改正

import java.util.Scanner;//求1+1/(2!)+1/(3!)+...+1/(n!)的和

public class e {

public static void main(String[] args) {
int i,sum=1;
double k,m=0;
Scanner sc=new Scanner(System.in);
System.out.println("请输入");
int j=sc.nextInt();
for( i=1;i<=j;i++)
{k=1/i;
sum*=k;System.out.println( j+"!="+sum );
m+=(1/(sum)); }System.out.println(m);

}
}

Answer 1

int sum = 1;
double result = 0;
Scanner sc = new Scanner(System.in);
System.out.println("请输入");
int j = sc.nextInt();
for (int i = 1; i <= j; i++) {
sum *= i;
result += (1.0 / sum);
System.out.println(i + "!=" + sum);
System.out.println("阶乘的倒数" + 1.0 / sum);
System.out.println("阶乘的倒数求和" + result);
}

Answer 2

package com.slxy.lianxi;
import java.util.Scanner;
//求1+1/(2!)+1/(3!)+...+1/(n!)的和
public class e {
/**求每一个数的阶乘 */
static double jie(int n){
double result=1;
for(int i=n;i>0;i--){
result = result*i;
}
return result;
}
/**对每一个数的阶乘分之一求和 */
static void sum(int n){
double sum=0;
for(int i=1;i<=n;i++){
sum = sum+1/jie(i);
}
System.out.println(sum);
}

public static void main(String[] args) {
System.out.println("要求几的阶乘，请输入该数：");
Scanner scan = new Scanner(System.in);
sum(scan.nextInt());
}
}

Answer 3

你这样的结果出现了1/0的情况，除数为0，会出现异常的。如果捕获异常的话，最终的结果是1.0。