suffix-array

I have read that the Longest Common Prefix (LCP) could be used to find the number of occurrences of a pattern in a string. Specifically, you just need to create the suffix array of the text, sort it, and then instead of doing binary search to find the range so that you can figure out the number of occurrences, you simply compute the LCP for each successive entry in the suffix array. Although using binary search to find the number of occurrences of a pattern is obvious I can't figure out how the LCP helps find the number of occurrences here. For example for this suffix array for banana : LCP

After quite a bit of reading, I have figured out what a suffix array and LCP array represents. Suffix array : Represents the _lexicographic rank of each suffix of an array. LCP array : Contains the maximum length prefix match between two consecutive suffixes, after they are sorted lexicographically . I have been trying hard to understand since a couple of days , how exactly the suffix array and LCP algorithm works. Here is the code , which is taken from Codeforces : /* Suffix array O(n lg^2 n) LCP table O(n) */ #include <cstdio> #include <algorithm> #include <cstring> using namespace std;

I'm looking for a fast suffix-array construction algorithm. I'm more interested in ease of implementation and raw speed than asymptotic complexity (I know that a suffix array can be constructed by means of a suffix tree in O(n) time, but that takes a lot of space; apparently other algorithms have bad worst-case big-O complexity, but run quite fast in practice). I don't mind algorithms that generate an LCP array as a by-product, since I need one anyway for my own purposes. I found a taxonomy of various suffix array construction algorithms , but it's out of date. I've heard of SA-IS , qsufsort ,

What would be the best approach (performance-wise) in solving this problem? I was recommended to use suffix trees. Is this the best approach? Have a look at http://en.wikipedia.org/wiki/Suffix_array as well - they are quite space-efficient and have some reasonably programmable algorithms to produce them, such as "Simple Linear Work Suffix Array Construction" by Karkkainen and Sanders user1071840 Check out this link: http://introcs.cs.princeton.edu/java/42sort/LRS.java.html /************************************************************************* * Compilation: javac LRS.java * Execution: java

From Section 15.2 of Programming Pearls The C codes can be viewed here: http://www.cs.bell-labs.com/cm/cs/pearls/longdup.c When I implement it in Python using suffix-array: example = open("iliad10.txt").read() def comlen(p, q): i = 0 for x in zip(p, q): if x[0] == x[1]: i += 1 else: break return i suffix_list = [] example_len = len(example) idx = list(range(example_len)) idx.sort(cmp = lambda a, b: cmp(example[a:], example[b:])) #VERY VERY SLOW max_len = -1 for i in range(example_len - 1): this_len = comlen(example[idx[i]:], example[idx[i+1]:]) print this_len if this_len > max_len: max_len =