编写递归西数求n!然后调用该函数求1!+21+3!+--+91。#include stdiohfloat fint nfloat У;if n==11n==0y=1；else12int main float s;int i;3for0=115=9;1++printfOfin5;

#include <stdio.h>

int factorial(int n) { if (n == 0) { return 1; } else { return n * factorial(n-1); } }

int main() { int sum = 0; for (int i = 1; i <= 9; i++) { int sign = (i % 2 == 0) ? -1 : 1; int term = sign * factorial(i); sum += term; } printf("1! + 2! - 3! + 4! - 5! + 6! - 7! + 8! - 9! = %d\n", sum); return 0; }