day11 part 2

JellevanKraaij · Dec 11, 2023 · de0a403 · de0a403
1 parent 58414fd
commit de0a403
Showing 1 changed file with 49 additions and 27 deletions.
diff --git a/day11/main.cpp b/day11/main.cpp
@@ -12,22 +12,24 @@ using SpaceCell = Type;
 using SpaceRow = vector<SpaceCell>;
 using Space = vector<SpaceRow>;
 
-void expandSpace(Space &space) {
-    // Horizontal
+vector<int> calcEmptyRows(const Space &space) {
+    vector<int> emptyRows;
     for (int i = 0; i < space.size(); i++) {
         bool hasGalaxy = false;
-        for (SpaceCell &cell : space[i]) {
+        for (const SpaceCell &cell : space[i]) {
             if (cell == GALAXY) {
                 hasGalaxy = true;
                 break;
             }
         }
-        if (!hasGalaxy) {
-            space.insert(space.begin() + i, SpaceRow(space[i].size(), EMPTY));
-            i++;
-        }
+        if (!hasGalaxy)
+            emptyRows.push_back(i);
     }
-    // Vertical
+    return emptyRows;
+}
+
+vector<int> calcEmptyColumns(const Space &space) {
+    vector<int> emptyColumns;
     for (int i = 0; i < space[0].size(); i++) {
         bool hasGalaxy = false;
         for (int j = 0; j < space.size(); j++) {
@@ -36,13 +38,31 @@ void expandSpace(Space &space) {
                 break;
             }
         }
-        if (!hasGalaxy) {
-            for (auto &row : space) {
-                row.insert(row.begin() + i, EMPTY);
+        if (!hasGalaxy)
+            emptyColumns.push_back(i);
+    }
+    return emptyColumns;
+}
+
+vector<pair<int, int>> findGalaxies(const Space &space) {
+    vector<pair<int, int>> galaxies;
+    for (int i = 0; i < space.size(); i++) {
+        for (int j = 0; j < space[i].size(); j++) {
+            if (space[i][j] == GALAXY) {
+                galaxies.push_back({i, j});
             }
-            i++;
         }
     }
+    return galaxies;
+}
+
+int passesEmptyRoC(const vector<int> &empty, int start, int end) {
+    int count = 0;
+    for (int i = start; i < end; i++) {
+        if (find(empty.begin(), empty.end(), i) != empty.end())
+            count++;
+    }
+    return count;
 }
 
 int main(int argc, char **argv) {
@@ -68,28 +88,30 @@ int main(int argc, char **argv) {
         space.push_back(row);
     }
 
-    expandSpace(space);
+    vector<int> emptyRows = calcEmptyRows(space);
+    vector<int> emptyColumns = calcEmptyColumns(space);
 
-    vector<pair<int, int>> galaxies;
+    vector<pair<int, int>> galaxies = findGalaxies(space);
 
-    for (int i = 0; i < space.size(); i++) {
-        for (int j = 0; j < space[i].size(); j++) {
-            if (space[i][j] == GALAXY) {
-                galaxies.push_back({i, j});
-            }
-        }
-    }
-
-    int total = 0;
-    int iteration = 0;
+    long total = 0;
+    long total2 = 0;
+    int galaxyCombinations = 0;
     for (auto it = galaxies.begin(); it != galaxies.end(); it++) {
         auto &[x1, y1] = *it;
         for (auto it2 = it + 1; it2 != galaxies.end(); it2++) {
             auto &[x2, y2] = *it2;
-            total += (max(x1, x2) - min(x1, x2)) + (max(y1, y2) - min(y1, y2));
-            iteration++;
+
+            int totalWithoutExpansion = (max(x1, x2) - min(x1, x2)) + (max(y1, y2) - min(y1, y2));
+
+            int emptyRowsCnt = passesEmptyRoC(emptyRows, min(x1, x2), max(x1, x2));
+            int emptyColumnsCnt = passesEmptyRoC(emptyColumns, min(y1, y2), max(y1, y2));
+
+            total += totalWithoutExpansion + emptyRowsCnt + emptyColumnsCnt;
+            total2 += totalWithoutExpansion + (emptyRowsCnt + emptyColumnsCnt) * 999999;
+            galaxyCombinations++;
         }
     }
     cout << "Total: " << total << endl;
-    cout << "GalaxyCount: " << iteration << endl;
+    cout << "Total2: " << total2 << endl;
+    cout << "GalaxyCount: " << galaxyCombinations << endl;
 }