init

Tries/Trie.java

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+/**
+ * Provides methods to manipulate the Trie. <br />
+ * The Trie only saves the root Node of which every Trie-Operation starts.
+ */
+public class Trie {
+
+    /**
+     * The root Node of the Trie.
+     */
+    private Node root;
+    /**
+     * creates new Trie.
+     */
+    public Trie() {
+        this.root = new Node();
+    }
+
+    /**
+     * adds new Student <code>key</code> with
+     * points <code>points</code> to the Trie.
+     * @param key Student to add
+     * @param points points of Student
+     * @return <code>true</code> if add was successful or <br />
+     *          <code>false</code> if Student already exists
+     */
+    public boolean add(String key, Integer points) {
+        Node iterator = this.root;
+        for (int i = 0; i < key.length(); i++) {
+            if (iterator.getChild(key.charAt(i)) == null) {
+                new Node(key.charAt(i), iterator);
+            }
+                iterator = iterator.getChild(key.charAt(i));
+        }
+        if (iterator.getPoints() == null) {
+            iterator.setPoints(points);
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * deletes Student <code>key</code> in the Trie.
+     * @param key Student to delete
+     * @return <code>true</code> if delete was successful or <br />
+     *          <code>false></code> if Student does not exist
+     */
+    public boolean delete(String key) {
+        Node hlp = this.root.find(key);
+        if (hlp == null) {
+            return false;
+        }
+        if (hlp.getPoints() != null) {
+            hlp.deleteMe();
+            return true;
+        } else {
+        return false;
+        }
+    }
+
+    /**
+     * changes points <code>points</code> of Student <code>key</code>
+     * in the Trie.
+     * @param key Student to change
+     * @param points points of Student to change
+     * @return <code>true</code> if change was successful or<br />
+     *          <code>false</code> if Student does not exist
+     */
+    public boolean change(String key, Integer points) {
+        Node hlp = this.root.find(key);
+        if (hlp == null) {
+            return false;
+        }
+        if (hlp.getPoints() != null) {
+            hlp.setPoints(points);
+            return true;
+        } else {
+        return false;
+        }
+    }
+
+    /**
+     * Getter for points of Student <code>key</code> in the Trie.
+     * @param key Student to search for
+     * @return <code>points</code> of Student or<br />
+     *          <code>null</code> if Student does not exist
+     */
+    public Integer points(String key) {
+        Node hlp = this.root.find(key);
+        if (hlp != null) {
+            return hlp.getPoints();
+        }
+        return null;
+    }
+
+    /**
+     * Method to print the hole Trie.
+     * @return <code>string</code> of the Trie in the requested format
+     */
+    public String toString() {
+        return this.root.toString();
+    }
+}