Fault table for KMP algorithm

fault_table.py

def construct_fault_table(pattern):
    fault_table = []
    fault_table.extend((0,0) # indexes 0 & 1 are always '0'
    j=0 # poniter to the prefix
    for i in xrange(2,len(pattern),1):
        if pattern[i] == pattern[j]:
            fault_table.append(fault_table[i-1]+1)
            j+=1
        else:
            j=0 # reset j to the start of the pattern if it breaks
            fault_table.append(0)
    return fault_table

print construct_fault_table('ABABE')
print construct_fault_table('ABABAC')
print construct_fault_table('ABACAB')