CODEWITHSUNDEEP
python-3.xstringmatchprefix
jason
jason

Reputation: 2106

How to find the overlap between first n string that match last n string in others python 3?

Assume I have two strings:

a = 'stackoverflow'
b =  'mathisgoodstackover'

I try to find the largest overlap part from the beginning of a that match the ending of b.

c= 'stackover'
d = 'stackoverf'

c is the optimal solution. d is not, since the b does not end with stackoverf.

I try to use brute-force, but not sure how to write the loop. any efficient algorithm?

Thanks,

Upvotes: 0

Views: 40

Answers (1)

kederrac
kederrac

Reputation: 17322

you can use the built-in function max with a list comprehension:

max([a[:i] for i in range(1,len(a) + 1) if b.endswith(a[:i])], key=len)

output:

'stackover'

also for special cases:

a = 'ssss'
b =  'mathisgoodssssss'
max([a[:i] for i in range(1,len(a) + 1) if a[:i] == b[-i:]], key=len)

outut:

'ssss'

or as suggested by @ShadowRanger you could start with i large as possible and then shrinking using next built-in function with a generator expression 

next((a[:i] for i in range(len(a), 0,-1) if b.endswith(a[:i])), '')

Upvotes: 2

Related Questions