algorithm-class/体系学习班/class32/Code03_AC1.java

package class32;

import java.util.LinkedList;
import java.util.Queue;

public class Code03_AC1 {

	public static class Node {
		public int end; // 有多少个字符串以该节点结尾
		public Node fail;
		public Node[] nexts;

		public Node() {
			end = 0;
			fail = null;
			nexts = new Node[26];
		}
	}

	public static class ACAutomation {
		private Node root;

		public ACAutomation() {
			root = new Node();
		}

		// 你有多少个匹配串，就调用多少次insert
		public void insert(String s) {
			char[] str = s.toCharArray();
			Node cur = root;
			int index = 0;
			for (int i = 0; i < str.length; i++) {
				index = str[i] - 'a';
				if (cur.nexts[index] == null) {
					Node next = new Node();
					cur.nexts[index] = next;
				}
				cur = cur.nexts[index];
			}
			cur.end++;
		}

		public void build() {
			Queue<Node> queue = new LinkedList<>();
			queue.add(root);
			Node cur = null;
			Node cfail = null;
			while (!queue.isEmpty()) {
				cur = queue.poll(); // 父
				for (int i = 0; i < 26; i++) { // 下级所有的路
					if (cur.nexts[i] != null) { // 该路下有子节点
						cur.nexts[i].fail = root; // 初始时先设置一个值
						cfail = cur.fail;
						while (cfail != null) { // cur不是头节点
							if (cfail.nexts[i] != null) {
								cur.nexts[i].fail = cfail.nexts[i];
								break;
							}
							cfail = cfail.fail;
						}
						queue.add(cur.nexts[i]);
					}
				}
			}
		}

		public int containNum(String content) {
			char[] str = content.toCharArray();
			Node cur = root;
			Node follow = null;
			int index = 0;
			int ans = 0;
			for (int i = 0; i < str.length; i++) {
				index = str[i] - 'a';
				while (cur.nexts[index] == null && cur != root) {
					cur = cur.fail;
				}
				cur = cur.nexts[index] != null ? cur.nexts[index] : root;
				follow = cur;
				while (follow != root) {
					if (follow.end == -1) {
						break;
					}
					{ // 不同的需求，在这一段{ }之间修改
						ans += follow.end;
						follow.end = -1;
					} // 不同的需求，在这一段{ }之间修改
					follow = follow.fail;
				}
			}
			return ans;
		}

	}

	public static void main(String[] args) {
		ACAutomation ac = new ACAutomation();
		ac.insert("dhe");
		ac.insert("he");
		ac.insert("c");
		ac.build();
		System.out.println(ac.containNum("cdhe"));
	}

}