Create 089. Gray Code.java

Author: futurus

089. Gray Code.java

@@ -0,0 +1,14 @@
+// https://leetcode.com/problems/gray-code
+// magical bit manipulation see https://en.wikipedia.org/wiki/Gray_code
+// doubt that it's possible to come up with this solution during 30 min interview without gray code familiarity!!!
+// though it might be possible to look at the reflection pattern and do it the long way
+public class Solution {
+    public List<Integer> grayCode(int n) {
+        List<Integer> result = new LinkedList<>();
+        
+        for (int i = 0; i < 1<<n; i++) 
+            result.add(i ^ i>>1);
+            
+        return result;
+    }
+}