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package class32;
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import java.util.ArrayList;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Queue;
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public class Code04_AC2 {
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// 前缀树的节点
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public static class Node {
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// 如果一个node，end为空，不是结尾
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// 如果end不为空，表示这个点是某个字符串的结尾，end的值就是这个字符串
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public String end;
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// 只有在上面的end变量不为空的时候，endUse才有意义
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// 表示，这个字符串之前有没有加入过答案
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public boolean endUse;
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public Node fail;
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public Node[] nexts;
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public Node() {
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endUse = false;
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end = null;
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fail = null;
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nexts = new Node[26];
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}
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}
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public static class ACAutomation {
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private Node root;
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public ACAutomation() {
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root = new Node();
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}
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public void insert(String s) {
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char[] str = s.toCharArray();
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Node cur = root;
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int index = 0;
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for (int i = 0; i < str.length; i++) {
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index = str[i] - 'a';
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if (cur.nexts[index] == null) {
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cur.nexts[index] = new Node();
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}
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cur = cur.nexts[index];
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}
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cur.end = s;
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}
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public void build() {
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Queue<Node> queue = new LinkedList<>();
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queue.add(root);
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Node cur = null;
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Node cfail = null;
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while (!queue.isEmpty()) {
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// 某个父亲，cur
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cur = queue.poll();
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for (int i = 0; i < 26; i++) { // 所有的路
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// cur -> 父亲 i号儿子，必须把i号儿子的fail指针设置好！
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if (cur.nexts[i] != null) { // 如果真的有i号儿子
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cur.nexts[i].fail = root;
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cfail = cur.fail;
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while (cfail != null) {
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if (cfail.nexts[i] != null) {
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cur.nexts[i].fail = cfail.nexts[i];
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break;
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}
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cfail = cfail.fail;
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}
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queue.add(cur.nexts[i]);
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}
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}
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}
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}
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// 大文章：content
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public List<String> containWords(String content) {
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char[] str = content.toCharArray();
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Node cur = root;
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Node follow = null;
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int index = 0;
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List<String> ans = new ArrayList<>();
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for (int i = 0; i < str.length; i++) {
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index = str[i] - 'a'; // 路
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// 如果当前字符在这条路上没配出来，就随着fail方向走向下条路径
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while (cur.nexts[index] == null && cur != root) {
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cur = cur.fail;
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}
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// 1) 现在来到的路径，是可以继续匹配的
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// 2) 现在来到的节点，就是前缀树的根节点
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cur = cur.nexts[index] != null ? cur.nexts[index] : root;
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follow = cur;
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while (follow != root) {
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if (follow.endUse) {
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break;
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}
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// 不同的需求，在这一段之间修改
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if (follow.end != null) {
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ans.add(follow.end);
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follow.endUse = true;
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}
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// 不同的需求，在这一段之间修改
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follow = follow.fail;
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}
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}
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return ans;
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}
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}
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public static void main(String[] args) {
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ACAutomation ac = new ACAutomation();
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ac.insert("dhe");
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ac.insert("he");
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ac.insert("abcdheks");
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// 设置fail指针
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ac.build();
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List<String> contains = ac.containWords("abcdhekskdjfafhasldkflskdjhwqaeruv");
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for (String word : contains) {
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System.out.println(word);
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}
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}
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}
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