Add Binary Exponentiation (#2359)

DivideAndConquer/BinaryExponentiation.java

@@ -0,0 +1,16 @@
+public class BinaryExponentiation {
+
+    public static void main(String args[]) {
+        System.out.println(calculatePower(2, 30));
+    }
+
+    // Function to calculate x^y
+    // Time Complexity: O(logn)
+    public static long calculatePower(long x, long y) {
+        if (y == 0) return 1;
+        long val = calculatePower(x, y / 2);
+        val *= val;
+        if (y % 2 == 1) val *= x;
+        return val;
+    }
+}