Create part1.cpp

part1.cpp

@@ -0,0 +1,99 @@
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <set>
+#include <stack>
+#include <cmath>
+using namespace std;
+
+#define isqrt(x) floor(sqrt(x))
+
+int Pair(int x, int y) {
+    if (x >= y) { return (x * x + x + y); }
+    else        { return (y * y + x    ); }
+}
+
+int UnPairY(int z) {
+    int sqrtz = isqrt(z);
+    int sqz = sqrtz * sqrtz;
+    return (z - sqz < sqrtz) ? sqrtz : z - sqz - sqrtz;
+}
+
+// return highest y
+int set_fill_range(int coords[], set<int> &obstacles, int cy) {
+    if (coords[0] == coords[2]) {
+        coords[0] = max(coords[1], coords[3]);
+        for (int x = min(coords[1], coords[3]); x <= coords[0]; x++) {
+            obstacles.insert(Pair(coords[2], x));
+        }
+    } else {
+        coords[1] = max(coords[0], coords[2]);
+        for (int x = min(coords[0], coords[2]); x <= coords[1]; x++) {
+            obstacles.insert(Pair(x, coords[3]));
+        }
+        if (cy < coords[3]) { return coords[3]; }
+    }
+    return cy;
+}
+
+int main() {
+    set<int> obstacles;
+    int highest_y = 0;
+
+    string line;
+    ifstream fp ("input.txt");
+    while (getline(fp, line)) {
+        int coordsTracker = 0;
+        int coords[4] = {0};
+        for (int i = 0; i < line.length(); i++) {
+            switch (line[i]) {
+                case ' ':
+                case '-':
+                    break;
+
+                case '>':
+                    if (coordsTracker == 3) {
+                        highest_y = set_fill_range(coords, obstacles, highest_y);
+
+                        coords[0] = coords[2];
+                        coords[1] = coords[3];
+                        coords[2] = 0;
+                        coords[3] = 0;
+
+                        coordsTracker = 1;
+                    }
+                case ',':
+                    coordsTracker++;
+                    break;
+
+                default:
+                    coords[coordsTracker] *= 10;
+                    coords[coordsTracker] += line[i] - '0';
+            }  
+        }
+        highest_y = set_fill_range(coords, obstacles, highest_y);
+    }
+
+    stack<int> sand_path;
+    int units = 0;
+
+    sand_path.push(250500);
+    while (UnPairY(sand_path.top()) < highest_y) {
+        int sand = sand_path.top() + 1;
+        if (obstacles.find(sand) == obstacles.end()) { sand_path.push(sand); }
+        else if (obstacles.find(sand - isqrt(4 * sand + 1) + 1) == obstacles.end()) {
+            sand_path.push(sand - isqrt(4 * sand + 1) + 1);
+
+        } else if (obstacles.find(sand + isqrt(4 * sand + 1) + 1) == obstacles.end()) {
+            sand_path.push(sand + isqrt(4 * sand + 1) + 1);
+
+        } else {
+            obstacles.insert(sand_path.top());
+            sand_path.pop();
+            units++;
+        }
+    }
+
+    cout << units << endl;
+    return 0;
+}