Regular Expression Matching

CMakeLists.txt

@@ -509,6 +509,7 @@ add_task(reconstruct-itinerary)
 add_task(recover-a-tree-from-preorder-traversal)
 add_task(recover-binary-search-tree)
 add_task(reducing-dishes)
+add_task(regular-expression-matching)
 add_task(remove-colored-pieces-if-both-neighbors-are-the-same-color)
 add_task(remove-duplicate-letters)
 add_task(remove-duplicates-from-sorted-array)

solutions/regular-expression-matching/CMakeLists.txt

@@ -0,0 +1 @@
+add_catch(test_regular_expression_matching test.cpp)

solutions/regular-expression-matching/solution.hpp

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <regex>
+#include <string>
+
+class Solution {
+public:
+  static bool isMatch(std::string s, std::string p) {
+    const int n = s.size(), m = p.size();
+
+    std::vector dp(n + 1, std::vector<bool>(m + 1));
+    dp[0][0] = true;
+
+    for (int j = 1; j <= m; ++j) {
+      dp[0][j] = p[j - 1] == '*' && dp[0][j - 2];
+    }
+
+    for (int i = 1; i <= n; ++i) {
+      for (int j = 1; j <= m; ++j) {
+        if (p[j - 1] == '*') {
+          if (p[j - 2] == '.' || p[j - 2] == s[i - 1]) {
+            dp[i][j] = dp[i][j - 2] || dp[i - 1][j];
+          } else {
+            dp[i][j] = dp[i][j - 2];
+          }
+        } else if (p[j - 1] == '.' || p[j - 1] == s[i - 1]) {
+          dp[i][j] = dp[i - 1][j - 1];
+        }
+      }
+    }
+
+    return dp[n][m];
+  }
+};

solutions/regular-expression-matching/test.cpp

@@ -0,0 +1,39 @@
+#include <catch.hpp>
+
+#include <solution.hpp>
+
+TEST_CASE("Simple") {
+  struct TestCase {
+    std::string s;
+    std::string p;
+    bool expected;
+  };
+
+  std::vector<TestCase> test_cases{
+      {
+          .s = "aa",
+          .p = "a",
+          .expected = false,
+      },
+      {
+          .s = "aa",
+          .p = "a*",
+          .expected = true,
+      },
+      {
+          .s = "ab",
+          .p = ".*",
+          .expected = true,
+      },
+      {
+          .s = "aa",
+          .p = "a*",
+          .expected = true,
+      },
+  };
+
+  for (const auto &[s, p, expected] : test_cases) {
+    const auto actual = Solution::isMatch(s, p);
+    REQUIRE(expected == actual);
+  }
+}

solutions/valid-number/test.cpp

@@ -11,7 +11,7 @@ TEST_CASE("VALID NUMBERS") {
   }
 }
 
-TEST_CASE("Not Valid Numbers") {
+TEST_CASE("NOT VALID NUMBERS") {
   std::vector<std::string> not_numbers{"abc", "1a",  "1e",       "e3", "99e2.5",
                                        "--6", "-+3", "95a54e53", ".",  "e"};
   for (const auto &not_number : not_numbers) {