Add solutions for "Day 7: Bridge Repair"

src/BridgeRepair.cpp

@@ -0,0 +1,95 @@
+// Solutions to the Advent Of Code 2024.
+// Copyright (C) 2025  Stefan Müller
+//
+// This program is free software: you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <aoc/BridgeRepair.hpp>
+
+#include <cmath>
+#include <sstream>
+
+#include <aoc/Math.hpp>
+
+const std::string BridgeRepair::getPuzzleName() const
+{
+    return "Day 7: Bridge Repair";
+}
+
+const std::string BridgeRepair::getInputFileName() const
+{
+    return "bridge_repair.txt";
+}
+
+void BridgeRepair::processDataLine(const std::string& line)
+{
+    std::istringstream stringStream{ line };
+
+    long long int testValue;
+    char colon;
+    int calibrationNumber;
+    // Calibration numbers are a pair of an actual calibration number and its precomputed smallest larger power of 10.
+    // The precomputed numbers are used to facilitate the "concatenate" operator.
+    std::vector<std::pair<int, int>> calibrationNumbers{};
+
+    stringStream >> testValue >> colon;
+    while (stringStream >> calibrationNumber)
+    {
+        // Skips the precomputation for the first calibration numbers.
+        int pow10{ 0 };
+        if (!calibrationNumbers.empty())
+        {
+            pow10 =  Math::ipow(10, static_cast<int>(floor(log10(calibrationNumber))) + 1);
+        }
+        calibrationNumbers.push_back({ calibrationNumber, pow10 });
+    }
+
+    if (testCalibration(testValue, calibrationNumbers, 1, false, calibrationNumbers[0].first))
+    {
+        part1 += testValue;
+        part2 += testValue;
+    }
+    else if (testCalibration(testValue, calibrationNumbers, 1, true, calibrationNumbers[0].first))
+    {
+        part2 += testValue;
+    }
+}
+
+void BridgeRepair::finish()
+{
+}
+
+bool BridgeRepair::testCalibration(const long long int testValue,
+    const std::vector<std::pair<int, int>>& calibrationNumbers, const size_t currentIndex,
+    const bool allowConcatenation, const long long int accumulatedTestValue)
+{
+    if (testValue >= accumulatedTestValue && currentIndex < calibrationNumbers.size())
+    {
+        size_t nextIndex{ currentIndex + 1 };
+        long long int nextCalibrationNumber{ calibrationNumbers[currentIndex].first };
+        // Recursively tries the ||, *, and + operators.
+        if ((allowConcatenation && testCalibration(testValue, calibrationNumbers, nextIndex, allowConcatenation,
+                accumulatedTestValue * calibrationNumbers[currentIndex].second + calibrationNumbers[currentIndex].first)) ||
+            testCalibration(testValue, calibrationNumbers, nextIndex, allowConcatenation,
+                accumulatedTestValue * calibrationNumbers[currentIndex].first) ||
+            testCalibration(testValue, calibrationNumbers, nextIndex, allowConcatenation,
+                accumulatedTestValue + calibrationNumbers[currentIndex].first))
+        {
+            return true;
+        }
+    }
+    else if (testValue == accumulatedTestValue)
+    {
+        return true;
+    }
+    return false;
+}

src/Math.cpp

@@ -0,0 +1,26 @@
+// Solutions to the Advent Of Code 2024.
+// Copyright (C) 2025  Stefan Müller
+//
+// This program is free software: you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <aoc/Math.hpp>
+
+int Math::ipow(const int base, const int exponent)
+{
+    int result = 1;
+    for (int i = 1; i <= exponent; i++)
+    {
+        result *= base;
+    }
+    return result;
+}

src/Program.cpp

@@ -27,6 +27,7 @@
 #include <aoc/CeresSearch.hpp>
 #include <aoc/PrintQueue.hpp>
 #include <aoc/GuardGallivant.hpp>
+#include <aoc/BridgeRepair.hpp>
 #include <aoc/HoofIt.hpp>
 #include <aoc/PlutonianPebbles.hpp>
 #include <aoc/LanParty.hpp>
@@ -53,6 +54,7 @@ void Program::runSolvers()
     runSolver<CeresSearch>(solverEngine);
     runSolver<PrintQueue>(solverEngine);
     runSolver<GuardGallivant>(solverEngine);
+    runSolver<BridgeRepair>(solverEngine);
     runSolver<HoofIt>(solverEngine);
     runSolver<PlutonianPebbles>(solverEngine);
     runSolver<LanParty>(solverEngine);