题目分析

CCF的第三道题，一般考察的是模拟和文本处理，题目难度不大，但是相当繁琐。按照题目的要求做，需要仔细认真的读题。我使用的是ArrayList解题，看到网上各位大佬使用的方法都是用树作为数据结构，可能这是我代码繁琐和最后出错的原因。

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {



    class HTMLElement
    {
        public String name;
        public String id;
        public int layer;

        public HTMLElement(String name, int layer) {
            this.name = name;
            this.layer = layer;
            this.id = null;
        }
    }


    public HTMLElement getLayers(String string)
    {
        char[] chars = string.toCharArray();
        int pointCount = 0;
        while(chars[pointCount]=='.')
        {
            pointCount++;
        }
        int layer = pointCount/2;
        String name = string.substring(pointCount,chars.length).toLowerCase();
        HTMLElement element = new HTMLElement(name,layer);
        return element;
    }

    public HTMLElement processString(String string)
    {
        String[] strings = string.split(" ");
        HTMLElement element = getLayers(strings[0]);
        if(strings.length==1)
        {
            return element;
        }
        element.id = strings[1];
        return element;
    }

    public ArrayList<Integer> findElements(ArrayList<HTMLElement> elements, String[] strings)
    {
        ArrayList<Integer> results = new ArrayList<Integer>();
        int ruleCounter = 0;
        int layerCounter = 0;
        boolean isStart = true;
        int lastCheckIndex = 0;
        for(int j=0;j<elements.size();j++)
        {
            HTMLElement curElement = elements.get(j);
            String s = curElement.name;
            if(strings[ruleCounter].startsWith("#"))
                s = curElement.id;
            if(s!=null&&isStart&&s.equals(strings[ruleCounter]))
            {
                layerCounter = curElement.layer;
                ruleCounter++;
                isStart = false;
                lastCheckIndex = j;
            }
            else if(!isStart&&curElement.layer<layerCounter)
            {
                ruleCounter = 0;
                isStart = true;
                j = lastCheckIndex;
            }
            else if(s!=null&&s.equals(strings[ruleCounter])&&curElement.layer>layerCounter)
            {
                layerCounter = curElement.layer;
                ruleCounter++;
            }
            if(ruleCounter==strings.length)
            {
                ruleCounter--;
                if(strings.length==1)
                    isStart = true;
                if(!results.contains(j+1))
                    results.add(j+1);
                //j = lastCheckIndex;
            }
        }

        int size = results.size();
        results.add(0,size);
        return results;
    }

    public void run() {
        ArrayList<HTMLElement> elements = new ArrayList<HTMLElement>();
        Scanner in = new Scanner(System.in);
        String num = in.nextLine();
        String[] nums = num.split(" ");
        int htmlLinesNum = Integer.valueOf(nums[0]);
        int searchNum = Integer.valueOf(nums[1]);
        for(int i=0;i<htmlLinesNum;i++)
        {
            try {
                String line = in.nextLine();
                HTMLElement element = processString(line);
                elements.add(element);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        for(int i=0;i<searchNum;i++)
        {
            try {
                String line = in.nextLine();
                ArrayList<Integer> integers = findElements(elements, line.split(" "));
                String s = "";
                for(Integer j:integers)
                {
                    s = s + " "+j.toString();
                }
                System.out.println(s);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

    public static void main(String[] args) {
        Main main = new Main();
        main.run();
    }
}