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Copy pathTrieTree.java
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130 lines (120 loc) · 3.91 KB
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package tree;
/**
* @Author: wei1
* @Date: Create in 2018/11/26 15:14
* @Description: 前缀树
*/
public class TrieTree {
public static class TrieNode {
public int path;
public int end;
public TrieNode[] nexts;
public TrieNode() {
path = 0;
end = 0;
nexts = new TrieNode[26];
}
}
public static class Trie {
private TrieNode root;
public Trie() {
this.root = new TrieNode();
}
public void insert(String word) {
if (word == null) {
return;
}
char[] chs = word.toCharArray();
TrieNode node = root;
int index = 0;
for (int i = 0; i < chs.length; i++) {
index = chs[i] - 'a';
if (node.nexts[index] == null) {
//这里你会发现这个字典树根本就没有存value
//而是通过index来标记所存的是啥字母
//所以要注意如果不是英文而是中文的化就要注意这个trienode中要存东西了
node.nexts[index] = new TrieNode();
}
node = node.nexts[index];
node.path++;
}
node.end++;
}
public int search(String word) {
if (word == null) {
return 0;
}
char[] chs = word.toCharArray();
TrieNode node = root;
int index = 0;
for (int i = 0; i < chs.length; i++) {
index = chs[i] - 'a';
if (node.nexts[index] != null) {
node = node.nexts[index];
} else {
return 0;
}
}
//返回有几个
return node.end;
}
public void delete(String word) {
//删除的逻辑就是删到了当前节点的path，就是经过此节点的数目为0就直接删掉后面的
if (search(word) != 0) {
char[] chs = word.toCharArray();
TrieNode node = root;
int index = 0;
for (int i = 0; i < chs.length; i++) {
index = chs[i] - 'a';
if (node.nexts[index] != null) {
TrieNode temp = node;
node = node.nexts[index];
node.path--;
if (node.path == 0) {
temp.nexts[index] = null;
return;
}
}
}
node.end--;
}
}
public int prefixNumber(String pre) {
if (pre == null) {
return 0;
}
char[] chs = pre.toCharArray();
TrieNode node = root;
int index = 0;
for (int i = 0; i < chs.length; i++) {
index = chs[i] - 'a';
if (node.nexts[index] == null) {
return 0;
}
node = node.nexts[index];
}
return node.path;
}
}
public static void main(String[] args) {
Trie trie = new Trie();
System.out.println(trie.search("zuo"));
trie.insert("zuo");
System.out.println(trie.search("zuo"));
trie.delete("zuo");
System.out.println(trie.search("zuo"));
trie.insert("zuo");
trie.insert("zuo");
trie.delete("zuo");
System.out.println(trie.search("zuo"));
trie.delete("zuo");
System.out.println(trie.search("zuo"));
trie.insert("zuoa");
trie.insert("zuoac");
trie.insert("zuoab");
trie.insert("zuoad");
trie.delete("zuoa");
System.out.println(trie.search("zuoa"));
System.out.println(trie.prefixNumber("zuo"));
}
}