Solved valid parentheses.

.vscode/settings.json

@@ -66,6 +66,7 @@
         "typeinfo": "cpp",
         "variant": "cpp",
         "format": "cpp",
-        "fstream": "cpp"
+        "fstream": "cpp",
+        "stack": "cpp"
     }
 }

CMakeLists.txt

@@ -39,3 +39,4 @@ add_subdirectory( longest-substring-without-repeating-characters )
 add_subdirectory( second-minimum-node-in-a-binary-tree )
 add_subdirectory( top-k-frequent-elements )
 add_subdirectory( two-sum )
+add_subdirectory( valid-parentheses )

valid-parentheses/CMakeLists.txt

@@ -0,0 +1,17 @@
+project(valid_parentheses)
+
+add_executable(
+  valid_parentheses_runner
+  runner.cpp
+)
+
+add_executable(
+  valid_parentheses_tests
+  tests.cpp
+)
+target_link_libraries(
+  valid_parentheses_tests
+  GTest::gtest_main
+)
+
+gtest_discover_tests(valid_parentheses_tests)

valid-parentheses/README.md

@@ -0,0 +1,3 @@
+# 20. Valid Parentheses
+
+[LeetCode link](https://leetcode.com/problems/valid-parentheses/)

valid-parentheses/runner.cpp

@@ -0,0 +1,13 @@
+#include <iostream>
+#include <string>
+
+#include "solution.hpp"
+
+int main()
+{
+    const std::string input("[]");
+    Solution s;
+    std::cout << "\"" << input << "\": " << (s.isValid(input) ? "true" : "false") << std::endl;
+
+    return 1;
+}

valid-parentheses/solution.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <stack>
+#include <string>
+
+class Solution {
+public:
+    bool isValid(const std::string& s) {
+        std::stack<char> st;
+        for (char c : s)
+        {
+            if (c == '(' || c == '[' || c == '{')
+                st.push(c);
+            else
+            {
+                if (st.empty())
+                    return false;
+                char curr = st.top();
+                st.pop();
+                if (c == ')' && curr != '(')
+                    return false;
+                else if (c == ']' && curr != '[')
+                    return false;
+                else if (c == '}' && curr != '{')
+                    return false;
+            }
+        }
+
+        return st.empty();        
+    }
+};

valid-parentheses/tests.cpp

@@ -0,0 +1,38 @@
+#include <gtest/gtest.h>
+
+#include <string>
+#include <utility>
+
+#include "solution.hpp"
+
+class ValidParenthesesTest :public ::testing::TestWithParam<std::pair<std::string, bool>> {
+protected:
+    Solution solution;
+};
+
+TEST_P(ValidParenthesesTest, CheckSolution) {
+    std::string input = std::get<0>(GetParam());
+    bool expected = std::get<1>(GetParam());
+
+    bool actual = solution.isValid(input);
+
+    EXPECT_EQ(expected, actual);
+}
+
+INSTANTIATE_TEST_SUITE_P(
+        ValidParenthesesTests,
+        ValidParenthesesTest,
+        ::testing::Values(
+                std::make_pair<std::string, bool>("{}", true),
+                std::make_pair<std::string, bool>("[]", true),
+                std::make_pair<std::string, bool>("()", true),
+                std::make_pair<std::string, bool>("{}{}[]", true),
+                std::make_pair<std::string, bool>("{{}}", true),
+                std::make_pair<std::string, bool>("{[]}", true),
+                std::make_pair<std::string, bool>("{", false),
+                std::make_pair<std::string, bool>("}", false),
+                std::make_pair<std::string, bool>(")()", false),
+                std::make_pair<std::string, bool>("(}", false),
+                std::make_pair<std::string, bool>("({)", false)
+                )
+        );