左程云基础班——前缀树
https://www.bilibili.com/video/BV13g41157hK?p=10&share_source=copy_web
1. 前缀树结点
边代表字母,结点存边的信息
private static class TreeNode {
public int pass;//经过此结点的边的数量
public int end;//以此边为结束
public TreeNode[] nexts;
public TreeNode() {
this.pass = 0;
this.end = 0;
this.nexts = new TreeNode[26];
}
}
2. CURD的实现
定义头结点
private TreeNode root;
1)增加前缀
public void insert(String word) {
if (word == null) {
return;
}
char[] chars = word.toCharArray();
TreeNode node = root;
int index = 0;
for (int i = 0; i < chars.length; i++) {
index = chars[i] - 'a';
if (node.nexts[index] == null) {
node.nexts[index] = new TreeNode();
}
node = node.nexts[index];
node.pass++;
}
node.end++;
}
2)查询前缀
//完整前缀
public int search(String word) {
if (word == null) {
return 0;
}
char[] chars = word.toCharArray();
TreeNode node = root;
int index = 0;
for (int i = 0; i < chars.length; i++) {
index = chars[i] - 'a';
if (node.nexts[index] == null) {
return 0;
}
node = node.nexts[index];
}
return node.end;
}
3)删除前缀
public void delete(String word) {
if (word == null || search(word) == 0) {
return;
}
char[] chars = word.toCharArray();
TreeNode node = root;
int index = 0;
for (int i = 0; i < chars.length; i++) {
index = chars[i] - 'a';
if (--node.nexts[index].pass == 0) {
node.nexts[index] = null;
return;
}
node = node.nexts[index];
}
node.end--;
}
4)示图
原文地址:https://blog.csdn.net/weixin_46731597/article/details/123619091
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