Bonus challenge for week 4

Week2.java

@@ -12,14 +12,27 @@ public class Week2 {
      * HINT: Solution 1 uses 1000 iterations in 1 loop. 
      */
     public static int problem1() {
-        return -1; // TODO
+        int sum = 0;
+
+        for(int i = 0; i < 1000; i++) {
+            if(i % 5 == 0 || i % 3 == 0) sum += i;
+        }
+
+        return sum;
     }
 
     /**
      * BONUS CHALLENGE: Find a more efficient solution for problem 1 (ie. a solution that uses less than 1000 iterations).
      */
     public static int problem2() {
-        return -1; // TODO
+        int sum = 0;
+        for(int i = 5; i < 1000; i+=5)
+            sum += i;
+
+        for(int i = 3; i < 1000; i+=3) 
+            if(i % 5 != 0) sum += i;
+
+        return sum;
     }
 
     /**

Week4Bonus.java

@@ -0,0 +1,26 @@
+/**
+ * In this week's club bonus challenge, you will be tasked with solving grid traversal problem.
+ */
+public class Week4 {
+
+    /**
+     * In a 2x2 grid, there are exactly 6 routes from the top-left corner to the bottom-right corner.
+     * Find an algorithm to find the number of routes in a 20x20 grid.
+     *
+     * Credit: Project Euler Problem 15.
+     *
+     * HINT: Recursion, recursion, recursion, recursion, recursion, recursion, recursion, recursion, recursion, recursion...
+     */
+    public static long problem1() {
+        return -1; // TODO
+    }
+
+    /**
+     * Test driver should not be edited!
+     */
+    public static void main(String[] args) {
+        long ans1 = problem1();
+
+        System.out.println(ans1 == 137846528820 ? "Problem 1 is correct!" : "Problem 1 (" + ans1 + ") is not correct...");
+    }
+}