程序代码：

#include "stdio.h"
main()
{
   float x,y;
   int k;
   scanf("%f",&x);
   if (x<1)
   k=0;
   else if(x>=1&&x<10)
   k=1;
   else if(x>10)
   k=2;
   switch (k)
   {
   case 0:
       y=x;break;
   case 1:
       y=2*x-1;break;
   case 2:
       y=3*x-11;break;
   }
   printf("y=%f",y);
}