alibaba 算法一面p7-高德（20220323）算法括号闭合问题

Posted 2022-03-26 史上最强的弟子

import java.util.*;

public class Main1 

    private  Map<Character,Character> map = new HashMap<>();

    private Set<Character> set = new HashSet<>();

    Main1()
        map.put('(',')');
        map.put('','');
        map.put('[',']');


        set.add('');
        set.add(']');
        set.add(')');
    

    public boolean check(String str)
        Stack<Character> stack = new Stack<>();
        Boolean flage = true;

        for(Character c:str.toCharArray())
            if(map.containsKey(c))
                stack.push(c);
                continue;
            
            if(set.contains(c))
                if(stack.isEmpty())
                    flage = false;
                    break;
                
                Character character = stack.pop();
                if(character == null)
                    flage = false;
                    break;
                
                if(!Objects.equals(map.get(character),c)) 
                   flage = false;
                   break;
                
            
        

        if(stack.size() !=0)
            flage = false;
        
        return flage;
    


    public static void main(String[] args) 
        Main1 main1 = new Main1();
        Boolean flag = main1.check("");
        System.out.println(flag);

        Boolean flag2 = main1.check("");
        System.out.println(flag2);

        Boolean flag3 = main1.check("]");
        System.out.println(flag3);

        Boolean flag4 = main1.check("[");
        System.out.println(flag4);

        Boolean flag5 = main1.check("[]");
        System.out.println(flag5);


        Boolean flag6 = main1.check("asdasdasd[asdasdasd]");
        System.out.println(flag6);

        Boolean flag7 = main1.check("");
        System.out.println(flag7);
    

输出结果：

 

 原理很简单，但是有一些边界条件需要注意。