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.
判断给定的字符串是否是合法的成对括号串
class Solution {
public:
    bool isPair(char left, char right){
        if(left==‘(‘&&right==‘)‘)return true;
        if(left==‘{‘&&right==‘}‘)return true;
        if(left==‘[‘&&right==‘]‘)return true;
        return false;
    }
    bool isValid(string s) {
        stack<int>st;
        for(int i=0; i<s.length(); i++){
            if(st.empty())st.push(s[i]);
            else{
                char left=st.top();
                if(isPair(left,s[i]))st.pop();
                else st.push(s[i]);
            }
        }
        return st.empty();
    }
};LeetCode: Valid Parentheses [020],布布扣,bubuko.com
LeetCode: Valid Parentheses [020]
原文地址:http://blog.csdn.net/harryhuang1990/article/details/25973405