Create letter-case-permutation.js

Create letter-case-permutation.js

Author: PranamBhat

JavaScript/letter-case-permutation.js

@@ -0,0 +1,21 @@
+/**
+ * @param {string} s
+ * @return {string[]}
+ */
+
+var letterCasePermutation = function(S) {
+    
+    S = S.toLowerCase()
+    let len = S.length, ans = []
+    const dfs = (i, res='') => {
+        if (i < len) {
+            dfs(i+1, res + S[i])
+            if (S[i] >= 'a') dfs(i+1, res + S[i].toUpperCase())
+        } else ans.push(res)
+    }
+    
+    dfs(0)
+    
+    return ans
+    
+};