Update AutoCompleteTrie.java

src/wordcorrector/AutoCompleteTrie.java

 package wordcorrector;
 
 import edu.caltech.cs2.datastructures.IterableString;
+import edu.caltech.cs2.datastructures.LinkedDeque;
+import edu.caltech.cs2.datastructures.TrieMap;
 import edu.caltech.cs2.interfaces.IDeque;
 
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.util.Iterator;
 import java.util.Scanner;
 import java.util.function.Function;
 
@@ -46,6 +49,31 @@ public class AutoCompleteTrie extends TrieMap<Character, IterableString, Integer
         return characters;
     }
 
+    protected TrieNode<Character, Integer> followKey(IterableString key) {
+        Iterator<Character> letters = key.iterator();
+        TrieNode<Character, Integer> current = this.root;
+        while (letters.hasNext()) {
+            Character letter = letters.next();
+            if (!current.pointers.containsKey(letter)) {
+                return null;
+            }
+            current = current.pointers.get(letter);
+        }
+        return current;
+    }
+
+    protected void getKeys(TrieNode<Character, Integer> current, IDeque<Character> keySoFar, IDeque<IterableString> keys) {
+        if (current.value != null) {
+            keys.add(super.collector.apply(keySoFar));
+        }
+
+        for (Character letter : current.pointers.keySet()) {
+            keySoFar.addBack(letter);
+            getKeys(current.pointers.get(letter), keySoFar, keys);
+            keySoFar.removeBack();
+        }
+    }
+
     /**
      * Retrieves keys that have the given key as a prefix
      */