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.
题意：括号匹配问题。
思路：利用栈来处理，判断右括号的情况
class Solution {public:bool isValid(string s) {stack<char> st;for (int i = 0; i < s.size(); i++) {if (s[i] == ')' || s[i] == ']' || s[i] == '}') {if (st.empty())return false;else {char tmp = st.top();st.pop();if ((tmp == '(' && s[i] != ')') || (tmp == '[' && s[i] != ']') || (tmp == '{' && s[i] != '}'))return false;}} else st.push(s[i]);}if (!st.empty())return false;return true;}};
，既有美妙的风景，也会有称不上景、只有风的地方。
