Homework 15

src/Domino.java

@@ -0,0 +1,37 @@
+public class Domino {
+
+    private int upsideValue;
+    private int downsideValue;
+
+    public Domino(int upsideValue, int downsideValue) {
+        this.upsideValue = upsideValue;
+        this.downsideValue = downsideValue;
+    }
+
+    public boolean has(int value) {
+        return upsideValue == value || downsideValue == value;
+    }
+
+    public boolean canBeNextTo(Domino other) {
+        return this.upsideValue == other.upsideValue
+                || this.upsideValue == other.downsideValue
+                || this.downsideValue == other.upsideValue
+                || this.downsideValue == other.downsideValue;
+    }
+
+    public int getUpsideValue() {
+        return upsideValue;
+    }
+
+    public void setUpsideValue(int upsideValue) {
+        this.upsideValue = upsideValue;
+    }
+
+    public int getDownsideValue() {
+        return downsideValue;
+    }
+
+    public void setDownsideValue(int downsideValue) {
+        this.downsideValue = downsideValue;
+    }
+}

src/H15.java

@@ -0,0 +1,53 @@
+import java.util.Arrays;
+
+public class H15 extends HelpCommands {
+
+    public static int ex45pg114(Node<Integer> lst, Node<Integer> p, Node<Integer> q) {
+        if (lst == q) {
+            return lst.getValue();
+        }
+        if (p == null || lst == p) {
+            return lst.getValue() + ex45pg114(lst.getNext(), null, q);
+        }
+        return ex45pg114(lst.getNext(), p, q);
+    }
+
+    public static int ex46pg114(Node<Integer> lst1, Node<Integer> lst2) {
+        if (lst1 == null && lst2 == null) {
+            return 0;
+        }
+        if (lst1 == null) {
+            return 1 + ex46pg114(null, lst2.getNext());
+        }
+        if (lst2 == null) {
+            return 1 + ex46pg114(lst1.getNext(), null);
+        }
+        return ex46pg114(lst1.getNext(), lst2.getNext());
+    }
+
+    public static int ex48pg115(Domino[] dominoBricks, Domino domino) {
+        int counter = 0;
+        for (Domino dominoBrick : dominoBricks) {
+            counter += domino.canBeNextTo(dominoBrick) ? 1 : 0;
+        }
+        return counter;
+    }
+
+    public static int ex52pg116(Node<int[]> node){
+        int unevenLotteries = 0;
+        while (node != null) {
+            if (Arrays.stream(node.getValue()).max().getAsInt() - Arrays.stream(node.getValue()).min().getAsInt() <= 20) {
+                unevenLotteries++;
+            }
+            node = node.getNext();
+        }
+        return unevenLotteries;
+    }
+
+    public static void main(String[] args) {
+        Node<Integer> exp = buildNodes(1, 2, 3, 4, 5, 6);
+        Node<Integer> exp2 = buildNodes(1, 2, 3, 4, 5, 6, 7, 8);
+        System.out.println(ex46pg114(exp, exp2));
+    }
+
+}

src/HelpCommands.java

@@ -638,4 +638,18 @@ public static Node<Integer> reverseNode(Node<Integer> fst) {
         return prev;
     }
 
+    public static <T> T valueAt(Node<T> node, int index) {
+        for (int i = 0; i < index; i++) {
+            node = node.getNext();
+        }
+        return node.getValue();
+    }
+
+    public static <T> Node<T> nodeAt(Node<T> node, int index) {
+        for (int i = 0; i < index; i++) {
+            node = node.getNext();
+        }
+        return node;
+    }
+
 }