leetcode Valid Parentheses 有效括号

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

exa:

"(){}[]"  true:

"{[()]}" true

"(}{}[]" false

按照括号规则必须首先出现‘（’或者‘{’，‘[’否则肯定不是合理括号组合，当‘（’或者‘{’，‘[’将对应的右括号')','}',']'入栈然后判断字符串下一个字符非‘（’或者‘{’，‘[’时是否等于刚刚入栈的字符即可：

class Solution {
private:
	stackss;
public:
    bool isValid(string s) {
		int l=s.length();
		if(l%2!=0||l==0)return false;
		int i;
		for(i=0;i