import java.util.Stack;
public class Solution {
    public boolean isValid(String s){
        Stack<Character> 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();
                if(c==')'&& topChar !='(')
                    return false;
                if(c==']'&& topChar !='[')
                    return false;
                if(c=='}'&& topChar !='{')
                    return false;
            }
        }

        return stack.isEmpty();
    }

    public static void main(String[] args){
        System.out.println((new Solution()).isValid("{{}}[][]"));
        System.out.println((new Solution()).isValid("{{}}[]["));
    }

}



写入main在编译器中自行调试