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Felix Steghofer
2022-12-04 01:25:28 +01:00
commit 3db4f94e6a
31 changed files with 2762 additions and 0 deletions
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/**
* Provides methods to manipulate single Nodes.<br />
* A Node represents a char in the Trie and provides a children-array
* that saves following chars. <br />The Node also saves the parent Node.
* if a character is the last one of a string that is set it contains points.
* <br /><br />i.e. if "hans" is set with 5 points, <code>points</code>
* of 's' is 5.
*/
public class Node {
/**
* the points of a Student.
*/
private Integer points;
/**
* Node array for children.
*/
private Node[] children = new Node[26];
/**
* Parent Node.
*/
private Node parent;
/**
* The Character of the Node.
*/
private char ch;
/**
* Constructor for root Node.
*/
public Node() {
this.points = null;
this.parent = null;
this.ch = '+';
}
/**
* Constructor for Node with character <code>ch</code>.
* @param ch character of the Node
*/
private Node(char ch) {
this.points = null;
this.parent = null;
this.ch = ch;
}
/**
* Constructor for Node <code>ch</code>s with known parent
* Node <code>parent</code>.
* @param ch character of the Node
* @param parent Parent Node of the Node
*/
public Node(char ch, Node parent) {
Node hlp = new Node(ch);
hlp.parent = parent;
parent.setChild(ch, hlp);
}
/**
* Converts a character <code>ch</code> into the index for
* the children array.
* @param ch character to convert
* @return index for the children array
*/
private int convertChar(char ch) {
return ch - 'a';
}
/**
* Sets <code>child</code> with character <code>ch</code>
* in children array.
* @param ch the child's character
* @param child the child Node
*/
private void setChild(char ch, Node child) {
this.children[convertChar(ch)] = child;
}
/**
* Child getter.
* @param ch character of child to get
* @return <code>Node</code> of child
* or <code>null</code>, if child does not exist
*/
public Node getChild(char ch) {
return this.children[convertChar(ch)];
}
/**
* Searches the subtree for a string <code>key</code>.
* @param key string to search for
* @return <code>Node</code> of found key or <code>null</code>
*/
public Node find(String key) {
int i = 1;
Node iterator = this.children[convertChar(key.charAt(0))];
while (iterator != null && i < key.length()) {
iterator = iterator.children[convertChar(key.charAt(i))];
i++;
}
if (i == key.length()) {
return iterator;
} else {
return null;
}
}
/**
* Reset <code>points</code> of Node.
*/
public void deleteMe() {
this.points = null;
cleanup();
}
/**
* Searches for children.
* @return <code>true</code>, if child was found or<br />
* <code>false</code>, if child not available
*/
private boolean hasChild() {
for (int i = 0; i < this.children.length; i++) {
if (this.children[i] != null) {
return true;
}
}
return false;
}
/**
* Deletes unneeded Nodes after Student deletion.
*/
private void cleanup() {
if (hasChild()) {
return;
}
Node iterator = this.parent;
char isChild = this.ch;
while (iterator.points == null && iterator.parent != null) {
//delete edge
iterator.children[convertChar(isChild)] = null;
//if another child is set, the Node is still needed
if (iterator.hasChild()) {
return;
}
isChild = iterator.ch;
iterator = iterator.parent;
}
//delete child Node in root
iterator.children[convertChar(isChild)] = null;
}
/**
* Method to print a Node and his subtree.<br />
* Recursive self-calling every child of the Node.
* @return <code>string</code> of Node and subtree
*/
public String toString() {
System.out.print(this.ch);
if (this.points != null) {
System.out.print("[" + this.points + "]");
}
if (this.hasChild()) {
System.out.print("(");
for (int i = 0; i < this.children.length; i++) {
if (this.children[i] != null) {
this.children[i].toString();
}
}
System.out.print(")");
}
return "";
}
/**
* Setter for points of Node.
* @param points to set
*/
public void setPoints(Integer points) {
this.points = points;
}
/**
* Getter for Points of Node.
* @return <code>points</code> of Node
*/
public Integer getPoints() {
return this.points;
}
}

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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
/**
* Main Class for the Student-Administration.<br />
* The user types commands and parameters to manipulate or change
* the Trie. <br />Commands are found with the HELP command
*/
final class Shell {
private Shell() { }
/**
* Checks if <code>string</code> consists of only chars.
* @param string String to check
* @return <code>true</code>, if <code>string</code> has only chars<br />
* <code>false</code>, if <code>string</code> has other signs
*/
private static boolean isCharString(String string) {
for (int j = 0; j < string.length(); j++) {
if (string.charAt(j) - 'a' < 0
|| string.charAt(j) - 'a' > 25) {
return false;
}
}
return true;
}
/**
* Main method for the Student Administration including the Shell.
* Validation for input.
* @param args are not handled at the moment
* @throws IOException
*/
public static void main(String[] args) throws IOException {
Trie t = new Trie();
boolean runtime = true;
BufferedReader br = new BufferedReader(
new InputStreamReader(System.in));
while (runtime) {
System.out.print("trie> ");
String input = br.readLine();
String[] splited = input.split(" ");
char ch = splited[0].charAt(0);
ch = Character.toLowerCase(ch);
try {
switch(ch) {
case 'n' :
if (splited.length != 1) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
t = new Trie();
break;
case 'a' :
if (splited.length != 3) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (!isCharString(splited[1])) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (Integer.parseInt(splited[2]) < 0) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (!t.add(splited[1], Integer.parseInt(splited[2]))) {
System.out.println("Error! " + splited[1]
+ " is already present.");
}
break;
case 'c' :
if (splited.length != 3) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (!isCharString(splited[1])) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (Integer.parseInt(splited[2]) < 0) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (!t.change(splited[1], Integer.parseInt(splited[2]))) {
System.out.println("Error! " + splited[1]
+ " does not yet exist");
}
break;
case 'd' :
if (splited.length != 2) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (!isCharString(splited[1])) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (!t.delete(splited[1])) {
System.out.println("Error! " + splited[1]
+ " does not yet exist");
}
break;
case 'p' :
if (splited.length != 2) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (!isCharString(splited[1])) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
if (t.points(splited[1]) != null) {
System.out.println(t.points(splited[1]));
} else {
System.out.println("Error! " + splited[1]
+ " does not yet exist");
}
break;
case 't' :
if (splited.length != 1) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
System.out.println(t.toString());
break;
case 'h' :
if (splited.length != 1) {
System.out.println("Error! Wrong Parameter! "
+ "check HELP");
break;
}
System.out.println("NEW Creates a new empty Trie ");
System.out.println("ADD adds <name> with <points>");
System.out.println("CHANGE change <points> of <name>");
System.out.println("DELETE deletes <name>");
System.out.println("POINTS displays points of <name>");
System.out.println("TRIE displays hole Trie");
System.out.println("HELP display this help");
System.out.println("QUIT exit Shell");
break;
case 'q' :
if (splited.length != 1) {
System.out.println("Error! Wrong Parameter! check HELP");
break;
}
runtime = false;
break;
default :
System.out.println("Error! Wrong command check HELP");
}
} catch (NumberFormatException e) {
System.out.println("Error! Wrong Parameter! check HELP");
}
}
}
}

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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();
}
}