參考文章:
https://mp.weixin.qq.com/s/hIU4gbKBNypsFWWVxx6x8Q 線段樹
https://github.com/liuyubobobo/Play-with-Algorithms
https://blog.csdn.net/qq_41479464/article/details/88586512 java貪心算法(線段樹)的詳細介紹(強推)
https://www.cnblogs.com/TheRoadToTheGold/p/6254255.html#undefined 淺談線段樹
線段樹是一個複雜的數據結構,大家如果不太懂,最好先找個視頻來看看,看懂了, 再去找相關的代碼或者博客去看,不然很容易迷糊的。
以下是線段樹的主體實現部分:
import java.util.TreeMap;
/// 使用TreeMap的Trie
public class Trie {
private class Node{
public boolean isWord;
public TreeMap<Character, Node> next;
public Node(boolean isWord){
this.isWord = isWord;
next = new TreeMap<>();
}
public Node(){
this(false);
}
}
private Node root;
private int size;
public Trie(){
root = new Node();
size = 0;
}
// 獲得Trie中存儲的單詞數量
public int getSize(){
return size;
}
// 向Trie中添加一個新的單詞word
public void add(String word){
Node cur = root;
for(int i = 0 ; i < word.length() ; i ++){
char c = word.charAt(i);
if(cur.next.get(c) == null)
cur.next.put(c, new Node());
cur = cur.next.get(c);
}
if(!cur.isWord){
cur.isWord = true;
size ++;
}
}
// 查詢單詞word是否在Trie中
public boolean contains(String word){
Node cur = root;
for(int i = 0 ; i < word.length() ; i ++){
char c = word.charAt(i);
if(cur.next.get(c) == null)
return false;
cur = cur.next.get(c);
}
return cur.isWord;
}
}
查詢 Trie 中是否有 isPrefix 爲前綴 的單詞
// 查詢是否在Trie中有單詞以prefix爲前綴
public boolean startsWith(String isPrefix){
Node cur = root;
for(int i = 0 ; i < isPrefix.length() ; i ++){
char c = isPrefix.charAt(i);
if(cur.next.get(c) == null)
return false;
cur = cur.next.get(c);
}
return true;
}