d4p2

day4/main.cpp

@@ -20,10 +20,10 @@ struct Diagram {
     size_t width;
     size_t height;
 
-    auto mdspan() const { return std::mdspan(data.data(), height, width); }
+    auto mdspan() { return std::mdspan(data.data(), height, width); }
 };
 
-auto printMap(const Diagram &diagram) {
+auto printMap(Diagram &diagram) {
     auto mdspan = diagram.mdspan();
     for (auto row = 0UZ; row != mdspan.extent(0); row++) {
         for (auto col = 0UZ; col != mdspan.extent(1); col++) {
@@ -48,8 +48,7 @@ auto parseMap(const std::string &filename) -> std::expected<Diagram, std::string
     while (std::getline(inputF, puzzleLine)) {
         // std::println("{:3}: {}", diagram.height, puzzleLine);
         diagram.data.push_back(0);
-        diagram.data.append_range(puzzleLine | std::views::transform([](char c) -> int { return c == '.' ? 0 : 1; }) |
+        diagram.data.append_range(puzzleLine | std::views::transform([](char c) -> int { return c == '.' ? 0 : 1; }));
-                                  std::ranges::to<std::vector<int>>());
         diagram.data.push_back(0);
         diagram.height++;
 
@@ -62,12 +61,12 @@ auto parseMap(const std::string &filename) -> std::expected<Diagram, std::string
     diagram.data.insert_range(diagram.data.begin(), std::vector<int>(diagram.width, 0));
     diagram.height += 2;
 
-    printMap(diagram);
+    // printMap(diagram);
-    //  auto ms2 = std::mdspan(diagram.data.data(), diagram.width, diagram.height);
+    //   auto ms2 = std::mdspan(diagram.data.data(), diagram.width, diagram.height);
     return std::move(diagram);
 }
 
-auto countMovablePaper(const Diagram &diagram) -> long {
+auto countMovablePaper(Diagram &diagram) -> long {
     long nMovablePaper{};
     auto mdspan = diagram.mdspan();
     for (auto row = 1UZ; row != mdspan.extent(0) - 1; row++) {
@@ -75,7 +74,7 @@ auto countMovablePaper(const Diagram &diagram) -> long {
 
             if (mdspan[row, col] == 1) {
                 // std::print("checking [{},{}]:", row, col);
-                //  shitty kernal
+                //  shitty kernel
                 int upLeft = mdspan[row - 1, col - 1];
                 int up = mdspan[row - 1, col];
                 int upRight = mdspan[row - 1, col + 1];
@@ -100,26 +99,74 @@ auto countMovablePaper(const Diagram &diagram) -> long {
     return nMovablePaper;
 }
 
+auto moveMoveablePaper(Diagram &diagram) -> long {
+    long totalPaperRemoved{};
+
+    auto mdspan = diagram.mdspan();
+
+    while (true) {
+        long currentPaperRemoved = 0;
+        for (auto row = 1UZ; row != mdspan.extent(0) - 1; row++) {
+            for (auto col = 1UZ; col != mdspan.extent(1) - 1; col++) {
+
+                if (mdspan[row, col] == 1) {
+                    // std::print("checking [{},{}]:", row, col);
+
+                    //  shitty kernal
+                    int neighbors{};
+                    neighbors += mdspan[row - 1, col - 1];
+                    neighbors += mdspan[row - 1, col];
+                    neighbors += mdspan[row - 1, col + 1];
+
+                    neighbors += mdspan[row, col - 1];
+                    neighbors += mdspan[row, col + 1];
+
+                    neighbors += mdspan[row + 1, col - 1];
+                    neighbors += mdspan[row + 1, col];
+                    neighbors += mdspan[row + 1, col + 1];
+
+                    // caveman shit
+                    if (neighbors < 4) {
+
+                        mdspan[row, col] = 0;
+                        // std::println("Found");
+                        currentPaperRemoved++;
+                    }
+                }
+                // std::println();
+            }
+        }
+        if (currentPaperRemoved == 0) {
+            std::println("Didn't remove any more paper this iteration! Stopping.");
+            break;
+        }
+        totalPaperRemoved += currentPaperRemoved;
+        // printMap(diagram);
+    }
+
+    return totalPaperRemoved;
+}
+
 auto main() -> int {
     auto testCase = parseMap("test_input");
     if (testCase) {
 
-        auto testResult = countMovablePaper(*testCase);
+        // auto testResult = countMovablePaper(*testCase);
-        std::println("P1 Testcase result: {}", testResult);
+        // std::println("P1 Testcase result: {}", testResult);
 
-        // auto testResultP2 = countMovablePaper(*testCase);
+        auto testResultP2 = moveMoveablePaper(*testCase);
-        // std::println("P2 Testcase result: {}", testResultP2);
+        std::println("P2 Testcase result: {}", testResultP2);
     } else {
         std::print("{}\n", testCase.error());
     }
 
     auto realPuzzle = parseMap("puzzle_input");
     if (realPuzzle) {
-        auto realResult = countMovablePaper(*realPuzzle);
+        //     auto realResult = countMovablePaper(*realPuzzle);
-        std::println("P1 Real result: {}", realResult);
+        //     std::println("P1 Real result: {}", realResult);
 
-        // auto realResultP2 = countJoltagesP2(*realPuzzle);
+        auto realResultP2 = moveMoveablePaper(*realPuzzle);
-        // std::println("P2 Real result: {}", realResultP2);
+        std::println("P2 Real result: {}", realResultP2);
     } else {
         std::print("{}\n", realPuzzle.error());
     }