first commit

lectures/lec1/Magic.java

@@ -0,0 +1,19 @@
+public class Magic {
+
+  public static void main(String[] args) {
+    System.out.println(magic());
+  }
+
+  int magic(int a, int n) {
+      int r = 1;
+      while (n != 0) {
+          if (n % 2 == 1) {
+              r *= a;
+          }
+          n /= 2;
+          a *= a;
+      }
+      return r;
+  }
+}
+