标签：called ret roo not bool null regular count arch
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 letters a-z or .. A . means it can represent any one letter.
For example:
addWord("bad")
addWord("dad")
addWord("mad")
search("pad") -> false
search("bad") -> true
search(".ad") -> true
search("b..") -> true
Note:
You may assume that all words are consist of lowercase letters a-z.
用Ｔrie树，如果碰到点（.），暴力地遍历当前ＴｒｉｅＮｏｄｅ下的所有节点
public class WordDictionary {
class TrieNode {
TrieNode[] children;
int count;
TrieNode() {
count = 0;
children = new TrieNode[26];
}
}
TrieNode root;
/** Initialize your data structure here. */
public WordDictionary() {
root = new TrieNode();
}
/** Adds a word into the data structure. */
public void addWord(String word) {
TrieNode cur = root;
int i = 0;
while (i < word.length()) {
if (cur.children[word.charAt(i) - ‘a‘] == null) {
cur.children[word.charAt(i) - ‘a‘] = new TrieNode();
}
cur = cur.children[word.charAt(i) - ‘a‘];
i++;
}
cur.count++;
}
/** 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 searchHelper(word, 0, root);
}
public boolean searchHelper(String word, int start, TrieNode node) {
// node != null
int i = start;
TrieNode cur = node;
while (i < word.length() && word.charAt(i) != ‘.‘) {
if (cur.children[word.charAt(i) - ‘a‘] == null) {
return false;
}
cur = cur.children[word.charAt(i) - ‘a‘];
i++;
}
// didn‘t meet ‘.‘
if (i == word.length()) {
if (cur.count == 0) {
return false;
} else {
return true;
}
}
// meet ‘.‘
for (int j = 0; j < 26; j++) {
if (cur.children[j] != null && searchHelper(word, i + 1, cur.children[j])) {
return true;
}
}
return false;
}
}
/**
* Your WordDictionary object will be instantiated and called as such:
* WordDictionary obj = new WordDictionary();
* obj.addWord(word);
* boolean param_2 = obj.search(word);
*/
211. Add and Search Word - Data structure design
标签：called ret roo not bool null regular count arch
原文地址：http://www.cnblogs.com/yuchenkit/p/7223488.html
