From 077b76336ec8e9dc7a6a7e4ea0905f300a7512cb Mon Sep 17 00:00:00 2001
From: Dheeraj Kumar Barnwal <dheerajraaj2@gmail.com>
Date: Tue, 3 Oct 2017 23:55:02 +0530
Subject: [PATCH] Trie Data structure

Trie Data structure implementation without any libraries
---
 data_structures/Trees/TrieImp.java | 135 +++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 data_structures/Trees/TrieImp.java

diff --git a/data_structures/Trees/TrieImp.java b/data_structures/Trees/TrieImp.java
new file mode 100644
index 00000000..c55586ff
--- /dev/null
+++ b/data_structures/Trees/TrieImp.java
@@ -0,0 +1,135 @@
+//Trie Data structure implementation without any libraries */
+
+/**
+ *
+ * @author Dheeraj Kumar Barnwal (https://github.com/dheeraj92)
+ *
+ */
+import java.util.Scanner;
+
+public class TrieImp {
+
+    public class TrieNode {
+        TrieNode[] child;
+        boolean end;
+
+        public TrieNode(){
+            child = new TrieNode[26];
+            end = false;
+        }
+    }
+    private final TrieNode root;
+    public TrieImp(){
+        root = new TrieNode();
+    }
+
+    public void insert(String word){
+        TrieNode currentNode = root;
+        for(int i=0; i < word.length();i++){
+            TrieNode node = currentNode.child[word.charAt(i)-'a'];
+            if(node == null){
+                node = new TrieNode();
+                currentNode.child[word.charAt(i)-'a']=node;
+            }
+            currentNode = node;
+        }
+        currentNode.end = true;
+    }
+    public boolean search(String word){
+        TrieNode currentNode = root;
+        for(int i=0;i<word.length();i++){
+            char ch = word.charAt(i);
+            TrieNode node = currentNode.child[ch-'a'];
+            if(node == null){
+                return false;
+            }
+            currentNode = node;
+        }
+        return currentNode.end;
+    }
+
+    public boolean delete(String word){
+        TrieNode currentNode = root;
+        for(int i=0;i<word.length();i++){
+            char ch = word.charAt(i);
+            TrieNode node = currentNode.child[ch-'a'];
+            if(node == null){
+                return false;
+            }
+            currentNode = node;
+        }
+        if(currentNode.end == true){
+            currentNode.end = false;
+            return true;
+        }
+        return false;
+    }
+
+    public static void sop(String print){
+        System.out.println(print);
+    }
+
+    //Regex to check if word contains only a-z character
+    public static boolean isValid(String word){
+        return word.matches("^[a-z]+$");
+    }
+
+    public static void main(String[] args) {
+        TrieImp obj = new TrieImp();
+        String word;
+        @SuppressWarnings("resource")
+        Scanner scan = new Scanner(System.in);
+        sop("string should contain only a-z character for all operation");
+        while(true){
+            sop("1. Insert\n2. Search\n3. Delete\n4. Quit");
+            try{
+                int t = scan.nextInt();
+                switch (t) {
+                    case 1:
+                        word = scan.next();
+                        if(isValid(word))
+                            obj.insert(word);
+                        else
+                            sop("Invalid string: allowed only a-z");
+                        break;
+                    case 2:
+                        word = scan.next();
+                        boolean resS=false;
+                        if(isValid(word))
+                            resS = obj.search(word);
+                        else
+                            sop("Invalid string: allowed only a-z");
+                        if(resS)
+                            sop("word found");
+                        else
+                            sop("word not found");
+                        break;
+                    case 3:
+                        word = scan.next();
+                        boolean resD=false;
+                        if(isValid(word))
+                            resD = obj.delete(word);
+                        else
+                            sop("Invalid string: allowed only a-z");
+                        if(resD){
+                            sop("word got deleted successfully");
+                        }else{
+                            sop("word not found");
+                        }
+                        break;
+                    case 4:
+                        sop("Quit successfully");
+                        System.exit(1);
+                        break;
+                    default:
+                        sop("Input int from 1-4");
+                        break;
+                }
+            }catch(Exception e){
+                String badInput = scan.next();
+                sop("This is bad input: " + badInput);
+            }
+        }
+    }
+
+}