title: Find the number of unique longest common subsequences
body: <p>For 2 strings, I want to find the number of distinct LCS's. I read on wiki on how to print all LCS's but how to check that they are distinct? The hash table is not feasible as my input string each can be 1500-2000 characters long so maximum number of LCS's can be 2000 choose 1000</p>