day 21: 20-valid-parentheses

started neetcode roadmap, finishing easy problems first

20-valid-parentheses/driver.cpp

@@ -0,0 +1,9 @@
+#include "soln.hpp"
+
+int main()	{
+	string s = "({[[[]]]})";
+	bool answer = true;
+	Solution soln;
+	cout << "Checked parentheses correctly? " << soln.test(s, answer) << endl;
+	return 0;
+}

20-valid-parentheses/soln.cpp

@@ -0,0 +1,42 @@
+#include "soln.hpp"
+
+bool Solution::isValid(string s)
+{
+	if (s.length() == 1)
+		return false;
+	vector<char> bstack;
+	for (char c : s)
+	{
+		switch (c)
+		{
+		case '(':
+		case '[':
+		case '{':
+			bstack.push_back(c);
+			break;
+		case ')':
+			if (bstack.size() < 1 || bstack.back() != '(')
+				return false;
+			else
+				bstack.pop_back();
+			break;
+		case ']':
+			if (bstack.size() < 1 || bstack.back() != '[')
+				return false;
+			else
+				bstack.pop_back();
+			break;
+		case '}':
+			if (bstack.size() < 1 || bstack.back() != '{')
+				return false;
+			else
+				bstack.pop_back();
+			break;
+		}
+	}
+	return bstack.size() == 0;
+}
+
+bool Solution::test(string s, bool answer)	{
+	return isValid(s) == answer;
+}

20-valid-parentheses/soln.hpp

@@ -0,0 +1,8 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution
+{
+public:
+	bool isValid(string s);
+	bool test(string s, bool answer);
+};