[manu2011]

Please help me with this one:

if s1 and s2 are two strings. we say that we extend s1 if we add a letter at the beginning or at the end of s1, but not in middle.
Ex: if s1=ababc. then both xababc and ababcx extend s1.

i have to design the best algorithm that checks if we can get from s1 to s2 by a sequence of extensions.

thanks

[mdhakk]

in this one I think you would start by ckecking if s1==s2. If it is not, I guess you could limit s2 to however many chars s1 has, and see if they match. If they dont, you could remove the first char from s2, and recheck to see if the second way works again. If you contiued doing that until s2 was the same amount of chars as s1, you would know whether or not it was possible.

[C.Ingram]

Locate s1 in s2. If s1 is not in s2 (and exists, of course), you cannot extend s1 so that is becomes s2. If s1 is in s2, then it must be possible to extened s1 until it is s2.

If:

s1 = abc

and

s2 = abcde OR s2= yzabc OR s2=1gj#$imgabcei$'h4

Then s1 can be extended into s2.

If

s1 = def

and

s2 = abcde OR s2= yzabc OR s2=1gj#$imgabcei$'h4

Then s1 cannot be extended into s2.