Add and Search Word

  1 public class WordDictionary {
  2 
  3     private TrieNode root = new TrieNode();
  4     // Adds a word into the data structure.
  5 
  6     public void addWord(String word) {
  7         if (search(word) == true) return;
  8 
  9         TrieNode current = root;
 10         for (int i = 0; i < word.length(); i++) {
 11             TrieNode child = current.subNode(word.charAt(i));
 12             if (child != null) {
 13                 current = child;
 14             } else {
 15                 current.childList.add(new TrieNode(word.charAt(i)));
 16                 current = current.subNode(word.charAt(i));
 17             }
 18             current.count++;
 19         }
 20         // Set isEnd to indicate end of the word
 21         current.isEnd = true;
 22     }
 23 
 24     // Returns if the word is in the trie.
 25     public boolean search(String word) {
 26         for (TrieNode child : root.childList) {
 27             if (search(child, word)) {
 28                 return true;
 29             }
 30         }
 31         return false;
 32     }
 33 
 34     public boolean search(TrieNode current, String word) {
 35         if (current == null) return false;
 36         if (word.length() == 0) return true;
 37 
 38         char c = word.charAt(0);
 39 
 40         if (word.length() == 1) {
 41             if (c == ‘.‘ && current.isEnd) 
 42                 return true;
 43             else if (current.content == c && current.isEnd)    
 44                 return true;
 45             else 
 46                 return false;
 47         } else {
 48             if (c == ‘.‘) {
 49                 for (TrieNode child : current.childList) {
 50                     if (search(child, word.substring(1))) {
 51                         return true;
 52                     }
 53                 }
 54                 return false;
 55             } else {
 56                 if (current.content == c) {
 57                     for (TrieNode child : current.childList) {
 58                         if (search(child, word.substring(1))) {
 59                             return true;
 60                         }
 61                     }
 62                     return false;
 63                 } else {
 64                     return false;
 65                 }
 66             }
 67         }
 68     }
 69 }
 70 
 71 // Your WordDictionary object will be instantiated and called as such:
 72 // WordDictionary wordDictionary = new WordDictionary();
 73 // wordDictionary.addWord("word");
 74 // wordDictionary.search("pattern");
 75 
 76 class TrieNode {
 77     // Initialize your data structure here.
 78     char content; // the character in the node
 79     boolean isEnd; // whether the end of the words
 80     int count; // the number of words sharing this character
 81     LinkedList<TrieNode> childList; // the child list
 82 
 83     public TrieNode() {
 84         childList = new LinkedList<TrieNode>();
 85         content = ‘ ‘;
 86     }
 87 
 88     public TrieNode(char c) {
 89         childList = new LinkedList<TrieNode>();
 90         content = c;
 91     }
 92 
 93     public TrieNode subNode(char c) {
 94         for (TrieNode eachChild : childList) {
 95             if (eachChild.content == c) {
 96                 return eachChild;
 97             }
 98         }
 99         return null;
100     }
101 }