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package learn.ds.string;

/**

* Rotate 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;

* 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.

* https://leetcode.com/problems/rotated-digits/description/

public class RotateDigits {

public static int validRotatedDigits(int N) {

int count = 0;

for(int i = 1 ; i <= N ; i++){

if (validate(i)) count++;

}

return count;

}

public static boolean validate(int N) {

boolean isValid = false;

while (N > 0) {

if (N % 10 == 2) isValid = true;

if (N % 10 == 5) isValid = true;

if (N % 10 == 6) isValid = true;

if (N % 10 == 9) isValid = true;

if (N % 10 == 3) return false;

if (N % 10 == 4) return false;

if (N % 10 == 7) return false;

N = N / 10;

}

return isValid;

}

public static void main(String[] args) {

System.out.println(validRotatedDigits(200));

}

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