//计算1！+2！-3！+4！-5！+……N！

#include <stdio.h> #include <math.h>

int main() { int n; int a = 1; int b = 0; int f = -1; int sum = 0; printf("计算1！+2！-3！+4！-5！+……N！\n"); printf("请输入N的值："); scanf_s("%d", &n); if (n == 1) { sum = 1; } else { for (int i = 1; i <= n; i++) { for (int j = 1; j <= i; j++) { a = a * j; } sum = sum + (a * f); f = -f; a = 1; } // 计算-1！+2！-3！+4！-5！+……N！的值 sum = sum + 2; //由于原题的第一项为正值，需要加2 } printf("结果为:%d", sum); return 0; }

#include<stdio.h>

int main() { int t; scanf("%d", &t); while (t--) { int n; scanf("%d", &n); if (n == 1) { printf("1\n"); } else { long long sum = 1; for (int a = 2; a <= n; a++) { long long ans = 1; if (a % 2 == 0) { for (int b = 1; b <= a; b++) { ans *= b; } sum += ans; } else { for (int b = 1; b <= a; b++) { ans *= (-b); } sum += ans; }

} printf("%lld\n", sum); }

} return 0;

}

#include <stdio.h>

int main()

{

int n;

scanf("%d",&n);

while(n--){

int a;

scanf("%d",&a);

if(a==1){

printf("%d\n",a);

}else if(a==2){

printf("%d\n",a+1);

}else if(a>2){

int ax=-1;

long long int sum=2,sam=3,ma=2;

for(int i=3;i<=a;i++){

if(i%2!=0){

ma=i*ma;

sum=ma*ax+sam;

sam=sum;

ax=1;

}else{

ma=i*ma;

sum=ma*ax+sam;

sam=sum;

ax=-1;

}

}

printf("%lld\n",sum);

}

}

return 0;

}

#include<stdio.h> int main(){ int t,n; scanf("%d",&t); for(int i=0;i<t;i++){ scanf("%d",&n); long long sum=1,sb=2; for(int j=1;j<=n;j++){ sum=jsum(-1); sb=sb+sum; } printf("%lld\n",sb); } return 0; }