add implementation for trie

Author: tamasbrandstadter

HolczerUdemyCourses/src/trees/avl/AVLTree.java renamed to HolczerUdemyCourses/src/tree/avl/AVLTree.java

@@ -1,4 +1,4 @@
-package trees.avl;
+package tree.avl;
 
 public class AVLTree<T extends Comparable<T>> implements Tree<T> {
  private Node<T> root;

HolczerUdemyCourses/src/trees/avl/Node.java renamed to HolczerUdemyCourses/src/tree/avl/Node.java

@@ -1,4 +1,4 @@
-package trees.avl;
+package tree.avl;
 
 public class Node<T> {
  private Node<T> left;

HolczerUdemyCourses/src/trees/avl/Tree.java renamed to HolczerUdemyCourses/src/tree/avl/Tree.java

@@ -1,4 +1,4 @@
-package trees.avl;
+package tree.avl;
 
 public interface Tree<T> {
  void insert(T data);

HolczerUdemyCourses/src/trees/binarysearch/BinarySearchTree.java renamed to HolczerUdemyCourses/src/tree/binarysearch/BinarySearchTree.java

@@ -1,4 +1,4 @@
-package trees.binarysearch;
+package tree.binarysearch;
 
 public class BinarySearchTree<T extends Comparable<T>> implements Tree<T> {
  private Node<T> root;

HolczerUdemyCourses/src/trees/binarysearch/Node.java renamed to HolczerUdemyCourses/src/tree/binarysearch/Node.java

@@ -1,4 +1,4 @@
-package trees.binarysearch;
+package tree.binarysearch;
 
 public class Node<T> {
  private Node<T> left;

HolczerUdemyCourses/src/trees/binarysearch/Tree.java renamed to HolczerUdemyCourses/src/tree/binarysearch/Tree.java

@@ -1,4 +1,4 @@
-package trees.binarysearch;
+package tree.binarysearch;
 
 public interface Tree<T> {
  void insert(T data);

HolczerUdemyCourses/src/trees/fenwick/FenwickTree.java renamed to HolczerUdemyCourses/src/tree/fenwick/FenwickTree.java

@@ -1,4 +1,4 @@
-package trees.fenwick;
+package tree.fenwick;
 
 // aka binary indexed tree
 public class FenwickTree {

HolczerUdemyCourses/src/tree/prefix/Node.java

@@ -0,0 +1,62 @@
+package tree.prefix;
+
+import static tree.prefix.Trie.ALPHABET_SIZE;
+
+public class Node {
+ private Node[] children;
+ private String character;
+ private int value;
+ private boolean isLeaf;
+ private boolean visited;
+
+ public Node(String character) {
+ this.children = new Node[ALPHABET_SIZE];
+ this.character = character;
+ }
+
+ public void setNode(int index, Node node, int value) {
+ node.setValue(value);
+ children[index] = node;
+ }
+
+ public Node[] getChildren() {
+ return children;
+ }
+
+ public void setChildren(Node[] children) {
+ this.children = children;
+ }
+
+ public String getCharacter() {
+ return character;
+ }
+
+ public void setCharacter(String character) {
+ this.character = character;
+ }
+
+ public boolean isLeaf() {
+ return isLeaf;
+ }
+
+ public void setLeaf(boolean leaf) {
+ isLeaf = leaf;
+ }
+
+ public int getValue() {
+ return value;
+ }
+
+ public void setValue(int value) {
+ this.value = value;
+ }
+
+ public boolean isVisited() {
+ return visited;
+ }
+
+ public void setVisited(boolean visited) {
+ this.visited = visited;
+ }
+
+}

HolczerUdemyCourses/src/tree/prefix/Trie.java

@@ -0,0 +1,107 @@
+package tree.prefix;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.lang.String.valueOf;
+
+public class Trie {
+ public static final int ALPHABET_SIZE = 26;
+ private Node root;
+ private int indexOfSingleChild;
+
+ public Trie() {
+ this.root = new Node("");
+ }
+
+ public void insert(String word, int value) {
+ Node temp = root;
+
+ for (int i = 0; i < word.length(); i++) {
+ char c = word.charAt(i);
+ int index = c - 'a';
+ if (temp.getChildren()[index] == null) {
+ Node node = new Node(valueOf(c));
+ temp.setNode(index, node, value);
+ temp = node;
+ } else {
+ temp = temp.getChildren()[index];
+ }
+ }
+
+ temp.setLeaf(true);
+ }
+
+ // O(m) running time complexity - where m is the length of the word
+ public boolean search(String word) {
+ Node temp = root;
+
+ for (int i = 0; i < word.length(); i++) {
+ char c = word.charAt(i);
+ int index = c - 'a';
+ if (temp.getChildren()[index] == null) {
+ return false;
+ } else {
+ temp = temp.getChildren()[index];
+ }
+ }
+
+ return true;
+ }
+
+ public List<String> allWordsWithPrefix(String prefix) {
+ Node temp = root;
+ List<String> words = new ArrayList<>();
+
+ for (int i = 0; i < prefix.length(); i++) {
+ char c = prefix.charAt(i);
+ int index = c - 'a';
+ temp = temp.getChildren()[index];
+ }
+
+ dfs(temp, prefix, words);
+
+ return words;
+ }
+
+ public String longestCommonPrefix() {
+ StringBuilder lcp = new StringBuilder();
+ Node temp = root;
+
+ while (childCount(temp) == 1 && !temp.isLeaf()) {
+ temp = temp.getChildren()[indexOfSingleChild];
+ lcp.append((char) (indexOfSingleChild + 'a'));
+ }
+
+ return lcp.toString();
+ }
+
+ private int childCount(Node node) {
+ int childrenCount = 0;
+ for (int i = 0; i < node.getChildren().length; i++) {
+ if (node.getChildren()[i] != null) {
+ childrenCount++;
+ indexOfSingleChild = i;
+ }
+ }
+
+ return childrenCount;
+ }
+
+ private void dfs(Node node, String prefix, List<String> words) {
+ if (node == null) {
+ return;
+ }
+ if (node.isLeaf()) {
+ words.add(prefix);
+ }
+
+ for (Node child : node.getChildren()) {
+ if (child == null) {
+ continue;
+ }
+ dfs(child, prefix + child.getCharacter(), words);
+ }
+ }
+
+}

HolczerUdemyCourses/src/trees/redblack/Color.java renamed to HolczerUdemyCourses/src/tree/redblack/Color.java

@@ -1,4 +1,4 @@
-package trees.redblack;
+package tree.redblack;
 
 public enum Color {
  RED, BLACK