A note on the longest common compatible prefix problem for partial words

For a partial word w the longest common compatible prefix of two positions i, j, denoted lccp(i,j), is the largest k such that w[i,i+k-1] and w[j,j+k-1] are compatible. The LCCP problem is to preprocess a partial word in such a way that any query lccp(i,j) about this word can be answered in O(1) time. We present a simple solution to this problem that works for any linearly-sortable alphabet. Our preprocessing is in time O(n?+n), where ? is the number of blocks of holes in w.