For a string P with characters P1, P2 ,…, Pq, let us denote by P[i, j] the substring Pi, Pi+1 ,…, Pj.
Defining longest common subsequence(LCS)
A subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements. LCS(A, B) of 2 sequences A and B is a subsequence, with maximal length, which is common to both the sequences.
Given a string S with small alphabet characters S1, S2 ,…, SN, return an array with two elements. First is the smallest j (1 ≤ j < N) for which
LCS(S[1, j], rev(S[j + 1, N])) is maximal and second is the maximal value of
LCS(S[1, j], rev(S[j + 1, N])).
rev(A) denotes reverse of string A.
S="abba" LCS(S[1, 1], rev(S[2, 4])) = LCS("a", "abb") = 1 LCS(S[1, 2], rev(S[3, 4])) = LCS("ab", "ab") = 2 LCS(S[1, 3], rev(S[4, 4])) = LCS("abb", "a") = 1 Hence, we return [2, 2].
NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a doubt? Checkout Sample Codes for more details.