2131

Author: orhtej2

CMakeLists.txt

@@ -47,3 +47,4 @@ add_subdirectory( kth-largest-element-in-a-stream )
 add_subdirectory( kth-largest-element-in-a-array )
 add_subdirectory( wiggle-sort-ii )
 add_subdirectory( longest-palindrome )
+add_subdirectory( longest-palindrome-by-concatenating-two-letter-words )

longest-palindrome-by-concatenating-two-letter-words/CMakeLists.txt

@@ -0,0 +1,25 @@
+project(longest_palindrome_2131)
+
+add_executable(
+  longest_palindrome_2131_runner
+  runner.cpp
+)
+
+add_executable(
+  longest_palindrome_2131_tests
+  tests.cpp
+)
+
+target_link_libraries(
+  longest_palindrome_2131_runner
+  utils
+)
+
+
+target_link_libraries(
+  longest_palindrome_2131_tests
+  GTest::gtest_main
+)
+
+
+gtest_discover_tests(longest_palindrome_2131_tests)

longest-palindrome-by-concatenating-two-letter-words/README.md

@@ -0,0 +1,3 @@
+# 2131. Longest Palindrome by Concatenating Two Letter Words
+
+[LeetCode link](https://leetcode.com/problems/longest-palindrome-by-concatenating-two-letter-words/)

longest-palindrome-by-concatenating-two-letter-words/runner.cpp

@@ -0,0 +1,16 @@
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include "print_vector.hpp"
+
+#include "solution.hpp"
+
+int main()
+{
+  const std::vector<std::string> input = { "aa", "bb", "ab", "bc", "bb"};
+    Solution s;
+    std::cout << input << ": " << s.longestPalindrome(input) << std::endl;
+
+    return 0;
+}

longest-palindrome-by-concatenating-two-letter-words/solution.hpp

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+class Solution {
+public:
+  int longestPalindrome(const std::vector<std::string>& words) {
+    std::unordered_map<std::string, int> known;
+    std::unordered_set<std::string> same;
+    int result = 0;
+    bool odd = false;
+    for (auto c : words) {
+      auto it = known.find(c);
+      if (it != known.end()) {
+        result += 4;
+        it->second--;
+        if (it->second == 0) {
+          known.erase(it);
+          same.erase(c);
+        }
+      }
+      else {
+        std::string reversed(c.rbegin(), c.rend());
+        known[reversed]++;
+        if (c[0] == c[1]) {
+          same.insert(c);
+        }
+      }
+    }
+
+    if (!same.empty()) {
+      result += 2;
+    }
+
+    return result;
+  }
+};

longest-palindrome-by-concatenating-two-letter-words/tests.cpp

@@ -0,0 +1,32 @@
+#include <gtest/gtest.h>
+
+#include <string>
+#include <utility>
+
+#include "solution.hpp"
+
+class LongestPalindromeTest :public ::testing::TestWithParam<std::pair<std::vector<std::string>, int>> {
+protected:
+    Solution solution;
+};
+
+TEST_P(LongestPalindromeTest, CheckSolution) {
+  std::vector<std::string> input = std::get<0>(GetParam());
+    int expected = std::get<1>(GetParam());
+
+    int actual = solution.longestPalindrome(input);
+
+    EXPECT_EQ(expected, actual);
+}
+
+INSTANTIATE_TEST_SUITE_P(
+  LongestPalindromeTests,
+  LongestPalindromeTest,
+        ::testing::Values(
+          std::make_pair<std::vector<std::string>, int>({ "aa" }, 2),
+          std::make_pair<std::vector<std::string>, int>({ "aa", "ab"}, 2),
+          std::make_pair<std::vector<std::string>, int>({ "ab", "ba"}, 4),
+          std::make_pair<std::vector<std::string>, int>({ "ab", "ba", "aa"}, 6),
+          std::make_pair<std::vector<std::string>, int>({ "qo","fo","fq","qf","fo","ff","qq","qf","of","of","oo","of","of","qf","qf","of" }, 14)
+        )
+);