Create Solution.java

Author: Jerring

solution/0784.Letter Case Permutation/Solution.java

@@ -0,0 +1,20 @@
+class Solution {
+    public List<String> letterCasePermutation(String S) {
+        char[] cs = S.toCharArray();
+        List<String> res = new ArrayList<>();
+        dfs(cs, 0, res);
+        return res;
+    }
+
+    private void dfs(char[] cs, int i, List<String> res) {
+        if (i == cs.length) {
+            res.add(String.valueOf(cs));
+            return;
+        }
+        dfs(cs, i + 1, res);
+        if (cs[i] >= 'A') {
+            cs[i] ^= 32;
+            dfs(cs, i + 1, res);
+        }
+    }
+}