longest_common_substring.py

def lcs(s1, s2):
    cols = len(s1) + 1
    rows = len(s2) + 1

    t = [[0 for i in range(cols)] for i in range(rows)]

    max_length = 0

    for i in range(1, rows):
        for j in range(1, cols):
            if s2[i-1] == s1[j-1]:
                t[i][j] = t[i-1][j-1] + 1
                max_length = max(max_length, t[i][j])

    return max_length