Problem Link - Interleaving String in Recursion
Problem Statement:
Given three strings s1
, s2
, and s3
, write a recursive function to determine if s3
can be obtained by interleaving s1
and s2
. An interleaving of two strings s1
and s2
is a configuration where they are merged in such a way that maintains the left-to-right order of characters from each string.
Approach:
- Base Case:
- If
s1
,s2
, ands3
are all empty, returntrue
. This means that we have successfully interleaved all characters froms1
ands2
to forms3
. - If
s3
is empty but eithers1
ors2
still has characters, returnfalse
. This means we couldn’t completely interleaves1
ands2
to forms3
.
- If
- Recursive Case:
- Check the first character of
s1
with the first character ofs3
. If they match, recursively check the remaining parts ofs1
,s3
, ands2
. - Similarly, check the first character of
s2
withs3
. If they match, recursively check the remaining parts ofs2
,s3
, ands1
. - If either recursive call returns
true
, we have found a valid interleaving.
- Check the first character of
Complexity:
- Time Complexity: For strings of length
n
, this approach can have an exponential time complexity, approximatelyO(2^n)
in the worst case because each recursive call has two possible branches (one fors1
and one fors2
). - Space Complexity: The space complexity is
O(n)
due to the depth of the recursive call stack.