LCP array

In computer science, the longest common prefix array (LCP array) is an auxiliary data structure to the suffix array. It stores the lengths of the longest common prefixes (LCPs) between all pairs of consecutive suffixes in a sorted suffix array.

LCP array
Type	Array
Invented by	Manber & Myers (1993)
Time complexity and space complexity in big O notation
Average Worst case Space ${\displaystyle {\mathcal {O}}(n)}$ ${\displaystyle {\mathcal {O}}(n)}$ Construction ${\displaystyle {\mathcal {O}}(n)}$ ${\displaystyle {\mathcal {O}}(n)}$

For example, if A := [aab, ab, abaab, b, baab] is a suffix array, the longest common prefix between A[1] = aab and A[2] = ab is a which has length 1, so H[2] = 1 in the LCP array H. Likewise, the LCP of A[2] = ab and A[3] = abaab is ab, so H[3] = 2.

Augmenting the suffix array with the LCP array allows one to efficiently simulate top-down and bottom-up traversals of the suffix tree, speeds up pattern matching on the suffix array and is a prerequisite for compressed suffix trees.