Leetcode 211: Add and Search Word, leetcodeadd

Leetcode 211: Add and Search Word, leetcodeadd
Add and Search Word-Data structure designTotal Accepted:1221Total Submissions:6120

Design a data structure that supports the following two operations:

void addWord(word)bool search(word)

Search (word) can search a literal word or a regular expression string containing only lettersa-zOr...Means it can represent any one letter.

For example:

addWord("bad")addWord("dad")addWord("mad")search("pad") -> falsesearch("bad") -> truesearch(".ad") -> truesearch("b..") -> true

Note:
You may assume that all words are consist of lowercase lettersa-z.

[Idea]

1. Use a set to save. Timeout.

2. Use trie for storage.

[CODE]

public class WordDictionary {    Set<String> dict = new HashSet<String>();    // Adds a word into the data structure.    public void addWord(String word) {        dict.add(word);    }    // Returns if the word is in the data structure. A word could    // contain the dot character '.' to represent any one letter.    public boolean search(String word) {        if(dict.contains(word) ) return true;        else if(!word.contains(".")) return false;                for(int c='a'; c<='z'; c++) {            int i=0;            while(word.charAt(i++) != '.'){}            StringBuilder sb = new StringBuilder(word);            sb.setCharAt(i-1, (char)c);            if( search(sb.toString()) ) return true;        }        return false;    }}

2. Create a Trie and search for it.

public class WordDictionary {    private TrieNode root = new TrieNode();    public void addWord(String word) {        Map<Character, TrieNode> children = root.children;        for(int i=0; i<word.length(); i++) {            char c = word.charAt(i);            TrieNode t;            if(children.containsKey(c)) {                t = children.get(c);            } else {                t = new TrieNode(c);                children.put(c, t);            }            children = t.children;            if(i==word.length()-1) t.leaf=true;        }    }    public boolean search(String word) {        return searchNode(word, root);    }        public boolean searchNode(String word, TrieNode tn) {        if(tn==null) return false;        if(word.length() == 0 ) return tn.leaf;                Map<Character, TrieNode> children = tn.children;        TrieNode t = null;        char c = word.charAt(0);        if(c=='.') {            for(char key : children.keySet() ) {                if(searchNode(word.substring(1), children.get(key) )) return true;            }            return false;        } else if(!children.containsKey(c)) {            return false;        } else {            t = children.get(c);            return searchNode(word.substring(1), t);        }    }    }class TrieNode {    // Initialize your data structure here.    char c;    boolean leaf;    HashMap<Character, TrieNode> children = new HashMap<Character, TrieNode>();        public TrieNode(char c) {        this.c = c;    }            public TrieNode(){};}