Give an O(nk) algorithm to find the optimal NoDeletion global alignment (note the improvement over the O(nm) algorithm when k is small), where a NoDeletion global alignment is an alignment between two sequences v = v₁ v₂ ... v_n and w = w₁ w₂ ... w_m where only matches, mismatches, and insertions are allowed and m >= n and k = m - n.