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括号匹配
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.
class Solution {
public:
bool isValid(string s) {
//use stack
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 c = st.top();
st.pop();
if ((c == ‘(‘ && s[i] != ‘)‘) || (c == ‘[‘ && s[i] != ‘]‘) || (c == ‘{‘ && s[i] != ‘}‘))
return false;
}
}
else
st.push(s[i]);
return st.empty();
}
};
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原文地址：http://www.cnblogs.com/chdxiaoming/p/4296089.html
