Description:
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.
解题思路：
详细参见之前博客
http://www.cnblogs.com/SYSU-Bango/p/6306962.html
代码：
class Solution { public: bool isValid(string str) { int count = 0; int size = str.length(); stack<char> temp; for (int i = 0; i < size; i++) { if (str[i] == ‘(‘ || str[i] == ‘[‘ || str[i] == ‘{‘) { temp.push(str[i]); } else { if (str[i] == ‘)‘) { if (!temp.empty() && temp.top() == ‘(‘) { temp.pop(); } else { //cout << "No" << endl; return false; count = 1; break; } } if (str[i] == ‘}‘) { if (!temp.empty() && temp.top() == ‘{‘) { temp.pop(); } else { //cout << "No" << endl; return false; count = 1; break; } } if (str[i] == ‘]‘) { if (!temp.empty() && temp.top() == ‘[‘) { temp.pop(); } else { //cout << "No" << endl; return false; count = 1; break; } } } } if (count == 0) { if (temp.empty() == true) { //cout << "Yes" << endl; return true; } else { //cout << "No" << endl; return false; } } } };
原文：http://www.cnblogs.com/SYSU-Bango/p/7676350.html