Letter Case Permutation

Author: Shikha-code36

Backtracking/784-letter-case-permutation.py

@@ -0,0 +1,27 @@
+''' Leetcode- https://leetcode.com/problems/letter-case-permutation/'''
+'''
+Given a string s, you can transform every letter individually to be lowercase or uppercase to create another string.
+
+Return a list of all possible strings we could create. Return the output in any order.
+
+ 
+Input: s = "a1b2"
+Output: ["a1b2","a1B2","A1b2","A1B2"]
+'''
+
+def letterCasePermutation(S):
+        S = S.lower()
+        lenS, ans = len(S), []
+        def dfs(i, res=''):
+            if i < lenS:
+                dfs(i+1, res + S[i])
+                if S[i].islower(): 
+                    dfs(i+1, res + S[i].upper())
+            else: 
+                ans.append(res)
+        dfs(0)
+        return ans
+
+print(letterCasePermutation("a1b2"))#['a1b2', 'a1B2', 'A1b2', 'A1B2']
+# T: O(M * 2^L)
+# S: O(L)

README.md

@@ -1,4 +1,6 @@
 # leetcode-solutions-python
 
 - [x] [Backtracking](Backtracking)
-    - [x] [Word Search](Backtracking/79-Word-Search.py)
+    - [x] [Word Search](Backtracking/79-Word-Search.py)
+    - [x] [Letter Case Permutation](Backtracking/784-letter-case-permutation.py)
+