【总结】使用字典树（Trie）寻找单词最短前缀

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前言

自己使用哈希表手实现了字典树的添加单词 addWord() 方法和查找单词最短前缀 searchPrefix() 方法.
此贴源于力扣第648题.单词替换

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一、代码实现

class TrieNode{
    char value;
    boolean isEnd;
    Map<Character, TrieNode> children;

    public TrieNode(char value) {
        this.value = value;
        this.children = new HashMap<>();
    }
}


class  TrieTree{
    TrieNode root;

    public TrieTree() {
        this.root = new TrieNode( ' ');
    }

    public void addWord(String word){
        TrieNode cur = root;
        for (char c : word.toCharArray()){
            if (! cur.children.containsKey(c)){
                cur.children.put(c, new TrieNode(c));
            }
            cur = cur.children.get(c);
        }
        cur.isEnd = true;
    }

    public int searchPrefix(String word){
        TrieNode cur = root;
        int len = 0;
        for (char c : word.toCharArray()){
            if (!cur.children.containsKey(c)){
                break;
            }else {
                cur = cur.children.get(c);
                len++;
                if (cur.isEnd)
                    return len;
            }
        }
        return -1;
    }
}