788. Rotated Digits Difficulty: Medium Topics: Senior , Math , Dynamic Programming , Weekly Contest 73 An integer x is a good 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. For example: 0 , 1 , and 8 rotate to themselves, 2 and 5 rotate to each other (in 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. Given an integer n , return the number of good integers in the range [1, n] . Example 1: Input: n = 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.…