Author: Vivek Kumar
This problem is pure implementation problem.
Now, suppose you know how to find the number of different substrings of a given string. So, to get Kth character in the concatenation of all substrings, You need to count the number of characters while calculating the length of LCP o ith and (i+1)th suffix in sorted order. Suppose length of the LCP is some L, and it was L’ between (i-1)th suffix and ith suffix. then ith suffix will contribute to strings having length L’+1, L’+2…L. and we will keep adding all the length in this manner unless we get length upto k.
The main issue in this problem is not the algorithm, but implementation
Author’s solution can be found here.