LeetCode 20 Valid Parentheses

翻译

给定一个只包含‘(‘, ‘)‘, ‘{‘, ‘}‘, ‘[‘ 和‘]‘的字符串，判断这个输入的字符串是否是有效的。

括号必须在正确的形式下闭合，"()" 和"()[]{}" 是有效的，但是 "(]" 和"([)]" 则不是。

原文

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.

代码

class Solution {
public:
    bool isValid(string s) {
        if(s.size() % 2 != 0) return 0;
        stack<char> brackets;
        int i = 0;
        while(i < s.size()) {
            if(brackets.empty()) {
                brackets.push(s[i]);
            } else {
                if((brackets.top() == ‘(‘ && s[i] == ‘)‘) ||
                (brackets.top() == ‘[‘ && s[i] == ‘]‘) ||
                (brackets.top() == ‘{‘ && s[i] == ‘}‘)) {
                    brackets.pop();
                } else {
                    brackets.push(s[i]);
                }
            }
            i ++;
        }
        return brackets.size() == 0;
    }
};