# Longest common subsequence problem

The longest common subsequence (LCS) problem is the problem of finding 
the longest subsequence common to all sequences in a set of sequences 
(often just two sequences). It differs from the longest common substring
problem: unlike substrings, subsequences are not required to occupy 
consecutive positions within the original sequences. 

## Application

The longest common subsequence problem is a classic computer science 
problem, the basis of data comparison programs such as the diff utility, 
and has applications in bioinformatics. It is also widely used by 
revision control systems such as Git for reconciling multiple changes 
made to a revision-controlled collection of files.

## Example

- LCS for input Sequences `ABCDGH` and `AEDFHR` is `ADH` of length 3.
- LCS for input Sequences `AGGTAB` and `GXTXAYB` is `GTAB` of length 4.

## References

- [Wikipedia](https://en.wikipedia.org/wiki/Longest_common_subsequence_problem)
- [YouTube](https://www.youtube.com/watch?v=NnD96abizww&list=PLLXdhg_r2hKA7DPDsunoDZ-Z769jWn4R8)