Create Find Kth Bit in Nth Binary String.java

varunu28 · web-flow · commit 3a2e60db99c4 · 2024-10-19T08:48:07.000-07:00
diff --git a/Medium/Find Kth Bit in Nth Binary String.java b/Medium/Find Kth Bit in Nth Binary String.java
@@ -0,0 +1,22 @@
+class Solution {
+    public char findKthBit(int n, int k) {
+        return nthString(n).charAt(k - 1);
+    }
+
+    private String nthString(int n) {
+        if (n == 1) {
+            return "0";
+        }
+        String prevString = nthString(n - 1);
+        return prevString + "1" + reverseAndInvert(prevString);
+    }
+
+    private String reverseAndInvert(String s) {
+        char[] chars = s.toCharArray();
+        for (int i = 0; i < s.length(); i++) {
+            chars[i] = chars[i] == '1' ? '0' : '1';
+        }
+        StringBuilder sb = new StringBuilder(String.valueOf(chars));
+        return sb.reverse().toString();
+    }
+}
