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| 1 | +//Trie Data structure implementation without any libraries */ |
| 2 | + |
| 3 | +/** |
| 4 | + * |
| 5 | + * @author Dheeraj Kumar Barnwal (https://github.com/dheeraj92) |
| 6 | + * |
| 7 | + */ |
| 8 | +import java.util.Scanner; |
| 9 | + |
| 10 | +public class TrieImp { |
| 11 | + |
| 12 | + public class TrieNode { |
| 13 | + TrieNode[] child; |
| 14 | + boolean end; |
| 15 | + |
| 16 | + public TrieNode(){ |
| 17 | + child = new TrieNode[26]; |
| 18 | + end = false; |
| 19 | + } |
| 20 | + } |
| 21 | + private final TrieNode root; |
| 22 | + public TrieImp(){ |
| 23 | + root = new TrieNode(); |
| 24 | + } |
| 25 | + |
| 26 | + public void insert(String word){ |
| 27 | + TrieNode currentNode = root; |
| 28 | + for(int i=0; i < word.length();i++){ |
| 29 | + TrieNode node = currentNode.child[word.charAt(i)-'a']; |
| 30 | + if(node == null){ |
| 31 | + node = new TrieNode(); |
| 32 | + currentNode.child[word.charAt(i)-'a']=node; |
| 33 | + } |
| 34 | + currentNode = node; |
| 35 | + } |
| 36 | + currentNode.end = true; |
| 37 | + } |
| 38 | + public boolean search(String word){ |
| 39 | + TrieNode currentNode = root; |
| 40 | + for(int i=0;i<word.length();i++){ |
| 41 | + char ch = word.charAt(i); |
| 42 | + TrieNode node = currentNode.child[ch-'a']; |
| 43 | + if(node == null){ |
| 44 | + return false; |
| 45 | + } |
| 46 | + currentNode = node; |
| 47 | + } |
| 48 | + return currentNode.end; |
| 49 | + } |
| 50 | + |
| 51 | + public boolean delete(String word){ |
| 52 | + TrieNode currentNode = root; |
| 53 | + for(int i=0;i<word.length();i++){ |
| 54 | + char ch = word.charAt(i); |
| 55 | + TrieNode node = currentNode.child[ch-'a']; |
| 56 | + if(node == null){ |
| 57 | + return false; |
| 58 | + } |
| 59 | + currentNode = node; |
| 60 | + } |
| 61 | + if(currentNode.end == true){ |
| 62 | + currentNode.end = false; |
| 63 | + return true; |
| 64 | + } |
| 65 | + return false; |
| 66 | + } |
| 67 | + |
| 68 | + public static void sop(String print){ |
| 69 | + System.out.println(print); |
| 70 | + } |
| 71 | + |
| 72 | + //Regex to check if word contains only a-z character |
| 73 | + public static boolean isValid(String word){ |
| 74 | + return word.matches("^[a-z]+$"); |
| 75 | + } |
| 76 | + |
| 77 | + public static void main(String[] args) { |
| 78 | + TrieImp obj = new TrieImp(); |
| 79 | + String word; |
| 80 | + @SuppressWarnings("resource") |
| 81 | + Scanner scan = new Scanner(System.in); |
| 82 | + sop("string should contain only a-z character for all operation"); |
| 83 | + while(true){ |
| 84 | + sop("1. Insert\n2. Search\n3. Delete\n4. Quit"); |
| 85 | + try{ |
| 86 | + int t = scan.nextInt(); |
| 87 | + switch (t) { |
| 88 | + case 1: |
| 89 | + word = scan.next(); |
| 90 | + if(isValid(word)) |
| 91 | + obj.insert(word); |
| 92 | + else |
| 93 | + sop("Invalid string: allowed only a-z"); |
| 94 | + break; |
| 95 | + case 2: |
| 96 | + word = scan.next(); |
| 97 | + boolean resS=false; |
| 98 | + if(isValid(word)) |
| 99 | + resS = obj.search(word); |
| 100 | + else |
| 101 | + sop("Invalid string: allowed only a-z"); |
| 102 | + if(resS) |
| 103 | + sop("word found"); |
| 104 | + else |
| 105 | + sop("word not found"); |
| 106 | + break; |
| 107 | + case 3: |
| 108 | + word = scan.next(); |
| 109 | + boolean resD=false; |
| 110 | + if(isValid(word)) |
| 111 | + resD = obj.delete(word); |
| 112 | + else |
| 113 | + sop("Invalid string: allowed only a-z"); |
| 114 | + if(resD){ |
| 115 | + sop("word got deleted successfully"); |
| 116 | + }else{ |
| 117 | + sop("word not found"); |
| 118 | + } |
| 119 | + break; |
| 120 | + case 4: |
| 121 | + sop("Quit successfully"); |
| 122 | + System.exit(1); |
| 123 | + break; |
| 124 | + default: |
| 125 | + sop("Input int from 1-4"); |
| 126 | + break; |
| 127 | + } |
| 128 | + }catch(Exception e){ |
| 129 | + String badInput = scan.next(); |
| 130 | + sop("This is bad input: " + badInput); |
| 131 | + } |
| 132 | + } |
| 133 | + } |
| 134 | + |
| 135 | +} |
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