leetcode Add and Search Word - Data structure design

最新推荐文章于 2021-10-19 01:15:14 发布

bleuesprit

最新推荐文章于 2021-10-19 01:15:14 发布

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本文介绍了一种使用前缀树（Trie）的数据结构来实现单词字典的方法，该方法支持单词的添加和搜索功能，特别是能够处理包含通配符'.'的模式匹配。

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题目链接

思路：
就是前缀树。如果碰到点符号就遍历好了，只要有一个返回true就返回true。。

class TrieNode {
    // Initialize your data structure here.
    TrieNode charecters[];
    boolean end;
    public TrieNode() {
        charecters=new TrieNode[26];
        end=false;
    }
}



public class WordDictionary {



    private TrieNode root;

    public WordDictionary() {
        root = new TrieNode();
        root.charecters=new TrieNode[26]; 
    }



    // Adds a word into the data structure.
    public void addWord(String word) {

        int n=word.length();
        TrieNode temp=root;
        for(int i=0;i<n;i++)
        {

            if(temp.charecters[word.charAt(i)-'a']==null)
            {
                temp.charecters[word.charAt(i)-'a']=new TrieNode();
            }
            temp=temp.charecters[word.charAt(i)-'a'];

        }
        temp.end=true;

    }

    // 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) {
        return searchHelp(word, 0,root);
    }

    public boolean searchHelp(String word,int currentIndex,TrieNode root)
    {
        if(currentIndex==word.length())
        {
            return root.end==true;
        }
        char targetChar=word.charAt(currentIndex);
        if(targetChar=='.')
        {
            for(int i=0;i<26;i++)
            {

                if(root.charecters[i]!=null&&searchHelp(word, currentIndex+1, root.charecters[i]))
                {
                    return true;
                }

            }


        }
        else
        {
            if(root.charecters[targetChar-'a']!=null)
            {
                return searchHelp(word, currentIndex+1, root.charecters[targetChar-'a']);
            }

        }



        return false;

    }
}

// Your WordDictionary object will be instantiated and called as such:
// WordDictionary wordDictionary = new WordDictionary();
// wordDictionary.addWord("word");
// wordDictionary.search("pattern");