add implementation for TST

Author: tamasbrandstadter

HolczerUdemyCourses/src/tree/prefix/Trie.java

@@ -14,11 +14,11 @@ public Trie() {
  this.root = new Node("");
  }
 
- public void insert(String word, int value) {
+ public void insert(String key, int value) {
  Node temp = root;
 
- for (int i = 0; i < word.length(); i++) {
- char c = word.charAt(i);
+ for (int i = 0; i < key.length(); i++) {
+ char c = key.charAt(i);
  int index = c - 'a';
  if (temp.getChildren()[index] == null) {
  Node node = new Node(valueOf(c));
@@ -32,12 +32,12 @@ public void insert(String word, int value) {
  temp.setLeaf(true);
  }
 
- // O(m) running time complexity - where m is the length of the word
- public boolean search(String word) {
+ // O(m) running time complexity - where m is the length of the key
+ public boolean search(String key) {
  Node temp = root;
 
- for (int i = 0; i < word.length(); i++) {
- char c = word.charAt(i);
+ for (int i = 0; i < key.length(); i++) {
+ char c = key.charAt(i);
  int index = c - 'a';
  if (temp.getChildren()[index] == null) {
  return false;

HolczerUdemyCourses/src/tree/ternarysearch/Node.java

@@ -0,0 +1,54 @@
+package tree.ternarysearch;
+
+public class Node {
+ private char c;
+ private Node left;
+ private Node middle;
+ private Node right;
+ private int value;
+
+ public Node(char c) {
+ this.c = c;
+ }
+
+ public char getCharacter() {
+ return c;
+ }
+
+ public void setCharacter(char c) {
+ this.c = c;
+ }
+
+ public Node getLeft() {
+ return left;
+ }
+
+ public void setLeft(Node left) {
+ this.left = left;
+ }
+
+ public Node getMiddle() {
+ return middle;
+ }
+
+ public void setMiddle(Node middle) {
+ this.middle = middle;
+ }
+
+ public Node getRight() {
+ return right;
+ }
+
+ public void setRight(Node right) {
+ this.right = right;
+ }
+
+ public int getValue() {
+ return value;
+ }
+
+ public void setValue(int value) {
+ this.value = value;
+ }
+
+}

HolczerUdemyCourses/src/tree/ternarysearch/TST.java

@@ -0,0 +1,58 @@
+package tree.ternarysearch;
+
+public class TST {
+ private Node root;
+
+ public void put(String key, int value) {
+ root = put(root, key, value, 0);
+ }
+
+ public Integer get(String key) {
+ Node node = get(root, key, 0);
+
+ if (node == null) {
+ return null;
+ }
+
+ return node.getValue();
+ }
+
+ private Node put(Node node, String key, int value, int index) {
+ char c = key.charAt(index);
+
+ if (node == null) {
+ node = new Node(c);
+ }
+ if (c < node.getCharacter()) {
+ node.setLeft(put(node.getLeft(), key, value, index));
+ } else if (c > node.getCharacter()) {
+ node.setRight(put(node.getRight(), key, value, index));
+ } else if (index < key.length() - 1){
+ node.setMiddle(put(node.getMiddle(), key, value, index + 1));
+ } else {
+ node.setValue(value);
+ }
+
+ return node;
+ }
+
+ // running time complexity is sub-linear in case of search misses
+ private Node get(Node node, String key, int index) {
+ if (node == null) {
+ return null;
+ }
+
+ char c = key.charAt(index);
+
+ if (c < node.getCharacter()) {
+ return get(node.getLeft(), key, index);
+ } else if (c > node.getCharacter()) {
+ return get(node.getRight(), key, index);
+ } else if (index < key.length() - 1) {
+ return get(node.getMiddle(), key, index + 1);
+ } else {
+ return node;
+ }
+ }
+
+}