1 class WordDictionary {
2 //使用什么来存储单词 ------>字典树？？
3
4 //字典树
5 // 1 新建节点
6 static class TireNode{
7 boolean flag ; //记录该单词是否出现
8 Map<Character, TireNode> childNode;
9
10 public TireNode()
11 {
12 flag = false;
13 childNode = new HashMap<Character, TireNode>();
14 }
15 }
16 TireNode node;
17
18 /** Initialize your data structure here. */
19 public WordDictionary() {
20 node = new TireNode(); //新建根节点,不存储任何字符
21 }
22
23 /** Adds a word into the data structure. */
24 //添加一个单词
25 public void addWord(String word) {
26 char[] letter = word.toCharArray();
27 TireNode curnode = node;
28 for(int i = 0 ; i < letter.length ; i++)
29 {
30 char cur = letter[i];
31 //从根节点寻找
32 if(!curnode.childNode.containsKey(cur)) //子节点不存在就添加
33 {
34 curnode.childNode.put(cur,new TireNode());
35 }
36 curnode = curnode.childNode.get(cur);
37 }
38 curnode.flag = true;
39
40 }
41
42 /** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */
43 public boolean search(String word) {
44 TireNode root = node;
45 return backstack(root,word,0);
46
47
48 }
49
50 private boolean backstack(TireNode root , String str, int index)
51 {
52 if(index == str.length())return root.flag;
53 char i = str.charAt(index);
54 if(i == '.')
55 {
56 //遍历当前节点下的所有子节点
57 for(Map.Entry<Character, TireNode> entry : root.childNode.entrySet()){
58 if(entry.getKey() != null && backstack(entry.getValue(),str,index+1))
59 {
60 //存在一个就返回true
61 return true;
62 }
63 }
64 return false;
65 }
66 else
67 {
68 if(!root.childNode.containsKey(i))
69 {
70 return false;
71 }
72 //直接进入下一个节点
73 return backstack(root.childNode.get(i),str , index+1);
74
75 }
76
77
78 }
79 }
