题解 | #括号序列#利用栈Stack FILO解决问题

import java.util.*;

import java.util.Stack;
public class Solution {
    /**
     * 
     * @param s string字符串 
     * @return bool布尔型
     */
    public boolean isValid (String s) {
        // write code here
        //利用栈 filo的性质来处理
        if(s.length() <= 1){
            return false;
        }
        Stack<Character> stack = new Stack();
        for(int i = 0;i < s.length();i++){
            char next = s.charAt(i);
            //遇到左括号就入栈
            if(next == '(' || next == '{' || next == '['){
                stack.push(next);
            } else {
                //出栈对比
                if(stack.isEmpty()){
                    return false;
                } else {
                    char c = stack.pop();
                    if((next == ')' && c != '(') || (next == '}' && c != '{') || (next == ']' && c != '[')){
                        return false;
                    }
                }
            }
        }
        if(stack.isEmpty()){
            return true;
        } else {
            return false;
        }
    }
}