File(s) Modified: 1980-find-unique-binary-string.java

Language(s) Used: java
Submission URL: https://leetcode.com/problems/find-unique-binary-string/submissions/1042550864/

Author: rkayan

java/1980-find-unique-binary-string.java

@@ -0,0 +1,39 @@
+class Solution {
+    /**
+     * If k is the length of the String and there are n Strings
+     * Time Complexity = O(2^k)
+     * Space Complexity = n*k (for set) + k (for the current sequence)
+     */
+    public String findDifferentBinaryString(String[] nums) {
+        Set<String> uniqueNums = Set.of(nums);
+        return helper(uniqueNums, uniqueNums.size(), new StringBuffer());
+    }
+
+    String helper(Set<String> uniqueStr, int size, StringBuffer currentSeq) {
+        //Check if current sequence has reached to required length
+        if (currentSeq.length() == size) {
+            //Check if current sequence exists in the provided list , we can keep track of it as global flag too
+            if (!uniqueStr.contains(currentSeq.toString())) {
+                return currentSeq.toString();
+            }
+            //current sequence is not unique
+            return null;
+        }
+
+        //Only if current sequence length is smaller than required length
+        currentSeq.append("0");
+        String result = helper(uniqueStr, size, currentSeq);
+        currentSeq.deleteCharAt(currentSeq.length() - 1);
+
+        //Check if we can find an ans with "0"
+        if (result != null) {
+            return result;
+        }
+        //If appending "0" didn't work then try with "1"
+        currentSeq.append("1");
+        result = helper(uniqueStr, size, currentSeq);
+        currentSeq.deleteCharAt(currentSeq.length() - 1);
+
+        return result;
+    }
+}