Editing Longest common subsequence (section)

=== Reduce the required space ===
If only the length of the LCS is required, the matrix can be reduced to a <math>2\times \min(n,m)</math> matrix, or to a <math>\min(m,n)+1</math> vector as the dynamic programming approach requires only the current and previous columns of the matrix. [[Hirschberg's algorithm]] allows the construction of the optimal sequence itself in the same quadratic time and linear space bounds.<ref>{{cite journal|author-link = Dan Hirschberg|author=Hirschberg, D. S.|title=A linear space algorithm for computing maximal common subsequences|journal=Communications of the ACM|volume=18|issue=6|year=1975|pages=341–343|doi=10.1145/360825.360861|s2cid=207694727|doi-access=free}}</ref>