Pythonic way to merge two overlapping lists, preserving order

Question

Alright, so I have two lists, as such:

• They can and will have overlapping items, for example, [1, 2, 3, 4, 5], [4, 5, 6, 7].
• The

Answer 1

I don't offer optimizations but another way of looking at the problem. To me, this seems like a particular case of http://en.wikipedia.org/wiki/Longest_common_substring_problem where the substring would always be at the end of the list/string. The following algorithm is the dynamic programming version.

def longest_common_substring(s1, s2):
    m = [[0] * (1 + len(s2)) for i in xrange(1 + len(s1))]
    longest, x_longest = 0, 0
    for x in xrange(1, 1 + len(s1)):
        for y in xrange(1, 1 + len(s2)):
            if s1[x - 1] == s2[y - 1]:
                m[x][y] = m[x - 1][y - 1] + 1
                if m[x][y] > longest:
                    longest = m[x][y]
                    x_longest = x
            else:
                m[x][y] = 0
    return x_longest - longest, x_longest

master = [1,3,9,8,3,4,5]
addition = [3,4,5,7,8]
s, e = longest_common_substring(master, addition)
if e - s > 1:
    print master[:s] + addition

master = [9, 1, 1, 8, 7]
addition = [8, 6, 7]
s, e = longest_common_substring(master, addition)
if e - s > 1:
    print master[:s] + addition
else:
    print master + addition

[1, 3, 9, 8, 3, 4, 5, 7, 8]
[9, 1, 1, 8, 7, 8, 6, 7]