【年少的风】求1/1!-1/3!+1/5!-1/7!……+(-1)^(n+1)/(2*n-1))

 

import java.util.*;
public class Test {

    public static void main(String[] args) {
        float sum = 1;
        int temp = 1;
        int n = 1;
        float flag = -1;

        System.out.print("请输入n的值：");
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();

        for(int i = 2; i <= n; i++){
            temp *= (2*i-1)*(2*i-2);
            flag *= -1;
            sum += flag/temp;
        }
        System.out.println("sum = " + sum);
    }
}