784

Author: ProHiryu

DFS/traditionalDFS/784.md

@@ -0,0 +1,35 @@
+## Is Graph Bipartite?
+
+#### Description
+
+[link](https://leetcode.com/problems/letter-case-permutation/)
+
+---
+
+#### Solution
+
+- See Code
+
+---
+
+#### Code
+
+> 最坏情况：O(n^2)
+
+```python
+class Solution:
+    def letterCasePermutation(self, S: str) -> List[str]:
+        res = []
+        self.dfs("", S, res)
+        return res
+
+    def dfs(self, pre, s, res):
+        if s == '':
+            res.append(pre)
+            return
+        if s[0].isdigit():
+            self.dfs(pre + s[0], s[1:], res)
+        else:
+            self.dfs(pre + s[0].lower(), s[1:], res)
+            self.dfs(pre + s[0].upper(), s[1:], res)
+```