finish lab2

lab2/Arithmetic/Arithmetic.java

@@ -20,6 +20,6 @@ public static int product(int a, int b) {
      * @return Sum of a and b
      * */
     public static int sum(int a, int b) {
-        return a * b;
+        return a + b;
     }
 }

lab2/DebugExercise/DebugExercise1.java

@@ -6,8 +6,8 @@
  */
 public class DebugExercise1 {
     public static int divideThenRound(int top, int bottom) {
-        int quotient = top / bottom;
-        int result = Math.round(quotient);
+        double quotient = (double) top / bottom;
+        int result = (int) Math.round(quotient);
         return result;
     }
 

lab2/DebugExercise/DebugExercise2.java

@@ -5,19 +5,20 @@
  * Code adapted from https://stackoverflow.com/questions/4895173/bitwise-multiply-and-add-in-java and https://stackoverflow.com/questions/1533131/what-useful-bitwise-operator-code-tricks-should-a-developer-know-about
  */
 public class DebugExercise2 {
-    /** Returns the max of a and b. Do not step into this function. */
+    /**
+     * Returns the max of a and b. Do not step into this function.
+     */
     public static int max(int a, int b) {
-        int w = (b - a) >> 31;
-        /* If you're stepping into this function, click the
-           step out button because you're not going to learn anything. */
-        int z = ~(b - a) >> 31;
-
-        int max = b & w | a & z;
-        return max;
+        if (a >= b) {
+            return a;
+        }
+        return b;
     }
 
 
-    /** Returns the sum of a and b. Do not step into this function. */
+    /**
+     * Returns the sum of a and b. Do not step into this function.
+     */
     public static int add(int a, int b) {
         int x = a, y = b;
         /* If you're stepping into this function, click the
@@ -35,10 +36,11 @@ public static int add(int a, int b) {
         return xor;
     }
 
-    /** Returns a new array where entry i is the max of
+    /**
+     * Returns a new array where entry i is the max of
      * a[i] and b[i]. For example, if a = {1, -10, 3}
      * and b = {0, 20, 5}, this function will return {1, 20, 5}.
-     * */
+     */
     public static int[] arrayMax(int[] a, int[] b) {
         if (a.length != b.length) {
             System.out.println("ERROR! Arrays don't match");
@@ -53,21 +55,24 @@ public static int[] arrayMax(int[] a, int[] b) {
         return returnArray;
     }
 
-    /** Returns the sum of all elements in x. */
+    /**
+     * Returns the sum of all elements in x.
+     */
     public static int arraySum(int[] x) {
         int i = 0;
         int sum = 0;
         while (i < x.length) {
-            sum = sum + add(sum, x[i]);
+            sum = sum + x[i];
             i = i + 1;
         }
         return sum;
     }
 
-    /** Returns the sum of the element-wise max of a and b.
-     *  For example if a = {2, 0, 10, 14} and b = {-5, 5, 20, 30},
-     *  the result should be 57.
-     * */
+    /**
+     * Returns the sum of the element-wise max of a and b.
+     * For example if a = {2, 0, 10, 14} and b = {-5, 5, 20, 30},
+     * the result should be 57.
+     */
     public static int sumOfElementwiseMaxes(int[] a, int[] b) {
         int[] maxes = arrayMax(a, b);
         int sumofMaxes = arraySum(maxes);

lab2/IntList/IntListExercises.java

@@ -10,7 +10,7 @@ public class IntListExercises {
      */
     public static void addConstant(IntList lst, int c) {
         IntList head = lst;
-        while (head.rest != null) {
+        while (head != null) {
             head.first += c;
             head = head.rest;
         }
@@ -51,7 +51,7 @@ public static int max(IntList L) {
      */
     public static boolean firstDigitEqualsLastDigit(int x) {
         int lastDigit = x % 10;
-        while (x > 10) {
+        while (x >= 10) {
             x = x / 10;
         }
         int firstDigit = x % 10;
@@ -77,6 +77,6 @@ public static boolean squarePrimes(IntList lst) {
             lst.first *= lst.first;
         }
 
-        return currElemIsPrime || squarePrimes(lst.rest);
+        return squarePrimes(lst.rest)||currElemIsPrime ;
     }
 }

lab2/IntList/SquarePrimesTest.java

@@ -17,4 +17,11 @@ public void testSquarePrimesSimple() {
         assertEquals("14 -> 15 -> 16 -> 289 -> 18", lst.toString());
         assertTrue(changed);
     }
+    @Test
+    public void testSquarePrimes2() {
+        IntList lst = IntList.of(11, 15, 16, 20, 13);
+        boolean changed = IntListExercises.squarePrimes(lst);
+        assertEquals("121 -> 15 -> 16 -> 20 -> 169", lst.toString());
+        assertTrue(changed);
+    }
 }

proj0/game2048/GUISource.java

@@ -35,16 +35,16 @@ class GUISource implements InputSource {
     public String getKey() {
         String command = _source.readKey();
         switch (command) {
-            case "↑" :
+            case "W" :
                 command = "Up";
                 break;
-            case "→" :
+            case "D" :
                 command = "Right";
                 break;
-            case "↓" :
+            case "S" :
                 command = "Down";
                 break;
-            case "←" :
+            case "A" :
                 command = "Left";
                 break;
             default :