Java 括号匹配问题案例详解

class MyStack{
    private int num;
    private LinkedList<Character> data;

    public MyStack(){
        this.num = 0;
        data = new LinkedList<Character>();
    }

    
    public boolean isEmpty(){
        return num == 0 ? true : false;
    }

    
    public void push(Character ch){
        this.data.add(ch);
        this.num++;
    }

    
    public Character pop(){
    	 //栈为空时，返回' '
        if(this.isEmpty()){
            return ' ';
        }
        Character ch = this.data.remove(data.size()-1);
        this.num--;
        return ch;
    }
}

    
    public boolean isValid(String s) {
        char[] temp = s.toCharArray();
        MyStack stack = new MyStack();
        boolean flag = true;
        for(int i = 0 ; i < temp.length ; i++){
            //左括号，入栈
            if(temp[i] == '(' || temp[i] == '{' || temp[i] == '['){
                stack.push(temp[i]);
            }
            else{
                //右括号，出栈
                char left = stack.pop();
                //如果从栈中取出空值，说明栈已空，但还有右括号存在，肯定不匹配
                if(left == ' ') {
                    flag = false;
                }
                //如果左右括号不匹配，则失败
                if(!check(left,temp[i])){
                    flag = false;
                }
            }
        }
        //循环完毕后，若栈不空，说明左括号个数大于右括号，不匹配
        if(flag){
            if(!stack.isEmpty()){
                flag = false;
            }
        }
        return flag;
    }
}

import java.util.LinkedList;




class MyStack{
    private int num;
    private LinkedList<Character> data;

    public MyStack(){
        this.num = 0;
        data = new LinkedList<Character>();
    }

    
    public boolean isEmpty(){
        return num == 0 ? true : false;
    }

    
    public void push(Character ch){
        this.data.add(ch);
        this.num++;
    }

    
    public Character pop(){
        //栈为空时，返回' '
        if(this.isEmpty()){
            return ' ';
        }
        Character ch = this.data.remove(data.size()-1);
        this.num--;
        return ch;
    }
}

class Solution {

    
    private boolean check(char left , char right){
        if(left == '('){
            return right == ')' ? true : false;
        }

        if(left == '['){
            return right == ']' ? true : false;
        }

        if(left == '{'){
            return right == '}' ? true : false;
        }
        return false;
    }

    
    public boolean isValid(String s) {
        char[] temp = s.toCharArray();
        MyStack stack = new MyStack();
        boolean flag = true;
        for(int i = 0 ; i < temp.length ; i++){
            //左括号，入栈
            if(temp[i] == '(' || temp[i] == '{' || temp[i] == '['){
                stack.push(temp[i]);
            }
            else{
                //右括号，出栈
                char left = stack.pop();
                //如果从栈中取出空值，说明栈已空，但还有右括号存在，肯定不匹配
                if(left == ' ') {
                    flag = false;
                }
                //如果左右括号不匹配，则失败
                if(!check(left,temp[i])){
                    flag = false;
                }
            }
        }
        //循环完毕后，若栈不空，说明左括号个数大于右括号，不匹配
        if(flag){
            if(!stack.isEmpty()){
                flag = false;
            }
        }
        return flag;
    }
}

public class Main {

    public static void main(String[] args) {
	// write your code here
        Solution solution = new Solution();
        System.out.println(solution.isValid("(({[]})"));
    }
}