Valid Parentheses

Desicription

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.

Solution

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class Solution {
public:
bool isValid(string s) {
stack<char> res;
for(int i = 0; s[i]; i++){
if(s[i] == '(' || s[i] == '[' || s[i] == '{')
res.push(s[i]);
else if(s[i] == ')'){
if(res.empty() || res.top() != '(')
return 0;
else
res.pop();
}
else if(s[i] == ']'){
if(res.empty() || res.top() != '[')
return 0;
else
res.pop();
}
else if(s[i] == '}'){
if(res.empty() || res.top() != '{')
return 0;
else
res.pop();
}
}
return res.empty();
}
};