LeetCode-Solutions/C++/valid-parentheses.cpp at master · spotpan/LeetCode-Solutions · GitHub

Repository navigation

// Time: O(n)

// Space: O(n)

class Solution {

public:

bool isValid(string s) {

const unordered_map<char, char> symbol_pair = {{')', '('},

{']', '['},

{'}', '{'}};

stack<char> parentheses;

for (const auto& c: s) {

const auto& it = symbol_pair.find(c);

if (it != symbol_pair.cend()) {

if (parentheses.empty() ||

parentheses.top() != it->second) {

return false;

}

parentheses.pop();

} else {

parentheses.emplace(c);

}

return parentheses.empty();

}

};