求多项式的和

1 #include 
     
       2  3 int main() 4 { 5     int m, n, i, f = -1; 6     double j,sum = 0; 7     while (scanf_s("%d", &m)) 8     { 9         for (i = 1;i <= m;i++)10         {11             scanf_s("%d",&n);12             f *= -1;13             j = 1.0 * f / i;14             sum += j;15             printf("%.2lf\n",sum);16         }17     }18     return 0;19 }
     

参考答案

1 #include
     
       2  3 int n; 4  5 double rev(int c) 6 { 7     return c <= n ?( ((c & 1) ? 1.0 : -1.0) / c + rev(c + 1) ): 0 ; 8 } 9 10 int main()11 {12     int t;13 14     scanf("%d", &t);15     while (t-- && scanf("%d", &n))16         printf("%.2lf\n", rev(1));17 18     return 0;19 }