import java.util.Stack;public class Solution {    public static void main(String[] args) {                Solution s = new Solution();                System.out.println(s.isValid("[]{"));            }                public boolean isValid(String s) {        //栈的特性：先进后出(后进先出 LIFO Last In First Out) 压栈 弹栈         Stack
        
          stack = new Stack<>();        for (int i = 0; i < s.length(); i++) {            char c = s.charAt(i);            if (c == '(' || c == '[' || c == '{') {                stack.push(c);            } else {                if (stack.isEmpty())                    return false;                char topChar = stack.pop();                //如果c 源值是 ( 且目标值不是反向C 表示两者并不是对立关系  返回false  匹配完必须是空                if (c == ')' && topChar != '(') {                    return false;                }                if (c == ']' && topChar != '[') {                    return false;                }                if (c == '}' && topChar != '{') {                    return false;                }            }        }        return stack.isEmpty();    }}