leetcode-20. Valid Parentheses

leetcode-20. Valid Parentheses

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.

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class Solution {
public:
bool isValid(string s) {
stack<char> p;
for(int i = 0; i < s.size(); ++i){
if(s[i] == '(' || s[i] == '[' || s[i] == '{')
p.push(s[i]);
else{
if(p.empty()) return false;
if(s[i] == ')' && p.top() != '(') return false;
if(s[i] == ']' && p.top() != '[') return false;
if(s[i] == '}' && p.top() != '{') return false;
else
p.pop();       //栈的操作，pop的时候直接pop就行，不用加参数
}
}
if(p.empty())
return true;
else
return false;
}
};