The problem calls digits in integer number "special" if they are "local maximum" (2 points) or "minimum" (1 point) among neighbors. And asks to calculate points for all numbers in a given range. It won't be hard for bruteforce if ranges are not on order 10^18
:) Thus it is most probable some kind of DP but I'm completely out of ideas how exactly to approach it. If someone can give such a subtle hint as direct me without spoiling the solution, it would be great!
Digit Dp
try to calculate it for all numbers from 0 till n1 and 0 till n2 and substract them for the answer in the range
let a be the first digit , b be the second digit and c be the third digit
we will have to add 2 when a < b and b > c or we will have to add 1 when a > b and b < c in the dp try to do something with this