题解 | #网购#

#include <stdio.h>

int main() {
   float a;
   int b,c = 0;
   scanf("%f",&a);
   scanf("%d %d",&b,&c);
   switch (b) {
    case 11:
        a = a * 0.7;
        break;
    case 12:
        a = a * 0.8;
        break;
   }
   int j;
   scanf("%d",&j);
   if (j == 1) {
        a = a - 50;
        if (a < 0) {
        a = 0;
        }
   }
  
   printf("%.2f",a);
   return 0;
}