Rotated digits

x is a good number if after rotating each digit individually by 180 degrees, we get a valid number that is different from x. Each digit must be rotated - we cannot choose to leave it alone.

A number is valid if each digit remains a digit after rotation. 0, 1, and 8 rotate to themselves; 2 and 5 rotate to each other (on this case they are rotated in a different direction, in other words 2 or 5 gets mirrored); 6 and 9 rotate to each other, and the rest of the numbers do not rotate to any other number and become invalid.

Now given a positive number n, how many numbers x from 1 to n are good?

Example:
Input: 10
Output: 4
Explanation: 
There are four good numbers in the range [1, 10] : 2, 5, 6, 9. 

Note that 1 and 10 are not good numbers, since they remain unchanged after rotating. 



c++ implementation:

    int rotatedDigits(int n) 
    {
        int c=0;
        while(n)
        {
            int x=n;
            int f=0;
            while(x)
            {
                int d=x%10;
                if(d==3 ||d==4||d==7)
                {
                  f=0;
                  break;
                }
                else if(d== 2 || d == 5 || d == 6 || d == 9)
                {
                   f=1;
                }
                x=x/10;  
            }
            if(f==1)
                c++;
            
            n=n-1;
        }
        return c;   
    }


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