Create 20. Valid Parentheses.cpp

Author: ZengruiWang

20. Valid Parentheses.cpp

@@ -0,0 +1,15 @@
+class Solution {
+public:
+    unordered_map<char, char> map = {{')','('}, {']', '['}, {'}', '{'}};
+    bool isValid(string s) {
+        vector<char> stack;
+        for(int i = 0; i < s.length(); ++i){
+            if(s[i] == '(' || s[i] == '{' || s[i] == '[')
+                stack.push_back(s[i]);
+            else if(!stack.empty() && map[s[i]] == stack.back())
+                stack.pop_back();
+            else return false;
+        }
+        return stack.empty();
+    }
+};