题解 | #机器人的运动范围#

思想很简单,但是超过时间了

import java.util.*;


public class Solution {
    /**
     * 
     * @param operators string字符串二维数组 the ops
     * @return string字符串一维数组
     */
    //operators[0][0] - 1,operators[0][1] - qwer
    //StringBuilder lastStr = new StringBuilder();
    ArrayList<String> lastStr = new ArrayList<String>();
    ArrayList<String> res = new ArrayList<String>();
    public String[] trieU (String[][] operators) {
        // write code here
        int len = operators.length;
        
        for(int i = 0;i<len;i++){
            String str = operators[i][0];
            switch(str){
                case "1":insert(operators[i][1]);
                    break;
                case "2":delete(operators[i][1]);
                    break;    
                case "3":search(operators[i][1]);
                    break;      
                case "4":prefixNumber(operators[i][1]);
                    break;   
            }//System.out.println(lastStr);
        }
        
        return res.toArray(new String[]{});
    }
    //1.增加
    public void insert(String word){
        lastStr.add(word);
    }
    //2.删除
    public void delete(String word){
        lastStr.remove(String.valueOf(word));
    }
    //3.查询
    public boolean search(String word){
        if(lastStr.indexOf(word)!=-1){
            res.add("YES");
            return true;
        }
        res.add("NO");
        return false;
    }
    //4.出现次数
    public int prefixNumber(String pre){
        int cnt = 0;
        for(int i = 0;i<lastStr.size();i++){
            if(lastStr.get(i).length() < pre.length()) continue;
            if(lastStr.get(i).substring(0, pre.length()).equals(pre)){
                cnt ++;
            }
        }
        res.add(cnt+"");
        return cnt;  
    }
}