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You are given a string S of length N . The string S consists of digits from 1-9. Consider the string indexing to be 1-based.
You need to divide the string into blocks such that the ith block contains the elements from the index((i−1)∗X+1) to min(N,(i∗X)) (both inclusive). A number is valid if it is formed by choosing exactly one digit from each block and placing the digits in the order of their block number.
For example:
If the given string is '123456789' and X=3, the blocks formed are [123], [456], [789]. Few valid numbers are 147,159,348 etc.. but 124 and 396 are invalid.
Among all the valid numbers that can be formed, your task is to determine the Kthnumber if all the unique valid numbers are sorted in ascending order.
Input format
Output format
Constraints
Note: Value of K will always be such that answer exists.
The string can be divided into 2 blocks as follows:
[12345] and [67891].
The 10th largest possible number is 29.