1259 Alice and Bob

      
      

       
       #include <stdio.h>
       
       

       
       #include <math.h>
       
       

       
       int 
       
       main()
       
       
{
       
       
    
       
       int 
       
       k;
       
       
    
       
       scanf(
       
       "%d",
       
       &
       
       k);
       
       
    
       
       while(
       
       k
       
       --)
       
       
    {
       
       
        
       
       int 
       
       n,
       
       m;
       
       
        
       
       scanf(
       
       "%d%d",
       
       &
       
       n,
       
       &
       
       m);
       
       
        
       
       __int64 
       
       count;
       
       
        
       
       if(
       
       n
       
       ==
       
       1)
       
       
        {
       
       
            
       
       count
       
       =
       
       9
       
       /
       
       m;
       
       
            
       
       printf(
       
       "%I64d\n",
       
       count
       
       +
       
       1);
       
       
        }
       
       
        
       
       else
       
       
        {
       
       
            
       
       __int64 
       
       a,
       
       b;
       
       //int a,b;太小,不能满足
       
       
            
       
       a
       
       =
       
       pow(
       
       10,
       
       n)
       
       -
       
       1;
       
       //pow()The function returns a floating point number,pow()-1后,因为a是整型数,will be automatically converted to an integer.
       
       
            
       
       a
       
       /=
       
       m;
       
       //Here is the integer calculation,The decimal point will be ignored,不会四舍五入
       
       
            
       
       b
       
       =
       
       pow(
       
       10,
       
       n
       
       -
       
       1)
       
       -
       
       1;
       
       //同上
       
       
            
       
       b
       
       /=
       
       m;
       
       
            
       
       count
       
       =
       
       a
       
       -
       
       b;
       
       
            
       
       printf(
       
       "%I64d\n",
       
       count);
       
       
        }
       
       
    }
       
       
    
       
       return 
       
       0;
       
       
}
      
      
      
      

       
       
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