Given a string S, we can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create.
Examples:
Input: S = "a1b2"
Output: ["a1b2", "a1B2", "A1b2", "A1B2"]
Input: S = "3z4"
Output: ["3z4", "3Z4"]
Input: S = "12345"
Output: ["12345"]
Note:
- S will be a string with length between 1 and 12.
- S will consist only of letters or digits.
class Solution:
def letterCasePermutation(self, S):
"""
:type S: str
:rtype: List[str]
"""
res = set()
def dfs(pos,s):
if pos==len(s):
return
if s[pos].isalpha():
res.add(s)
dfs(pos+1,s)
s = s[0:pos]+s[pos].swapcase()+s[pos+1:]
res.add(s)
dfs(pos+1,s)
else:
dfs(pos+1,s)
dfs(0,S)
return list(res) if len(res)>0 else [S]