Added Maximum Array XOR problem

Author: Karnika06

Codechef Problems/FlappyBird.java

@@ -0,0 +1,50 @@
+/*
+ * Implementation of Maximum Array XOR problem from CodeChef
+ * 
+ * Problem name: Maximum Array XOR problem
+ * Problem code: MAXARXOR
+ * Problem link: https://www.codechef.com/START7C/problems/MAXARXOR
+ */
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class MaximumArrayXOR
+{
+    public static void main (String[] args) throws java.lang.Exception
+    {
+        Scanner sc=new Scanner(System.in);
+        int t=sc.nextInt();
+        
+        while(t-->0)
+        {
+            long count=0;
+            long N=sc.nextInt();
+            long K=sc.nextInt();
+            
+            count=(long)Math.pow(2,N);
+            
+            if(K>=count/2)
+            K=count/2;
+            
+            count=(count-1)*K*2;
+        
+            System.out.println(count);
+            
+        }
+    }
+}
+/*
+ * Sample Input 1 
+ * 3
+ * 2 0
+ * 2 1
+ * 10 100
+ * 
+ * Sample Output 1 
+ * 0
+ * 6
+ * 204600
+ * 
+ * Time complexity: O(n)
+ */