2024 day 18

2024/18/main.cpp

@@ -0,0 +1,58 @@
+#include "../../include/aoc.hpp"
+#include <bits/stdc++.h>
+using namespace std;
+
+unordered_map<icoord, int> m;
+const int smax = 70;
+
+void rec(icoord c, int score) {
+	if (!m.contains(c)) {
+		return;
+	}
+
+	int &s = m[c];
+	if (s != -1 && s <= score) {
+		return;
+	}
+
+	s = score;
+	score++;
+
+	rec(c + icoord(1, 0), score);
+	rec(c + icoord(-1, 0), score);
+	rec(c + icoord(0, 1), score);
+	rec(c + icoord(0, -1), score);
+}
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	string line;
+	bool inits[smax + 1][smax + 1] = {};
+	int i = 0;
+	while (getline(cin, line) && !line.empty()) {
+		// NOTE: found part 2 is just binary search on this number until you
+		// stop getting -1 as output
+		if (++i > 1024) {
+			break;
+		}
+		istringstream l(line);
+		int x, y;
+		l >> x;
+		l.ignore();
+		l >> y;
+		inits[x][y] = true;
+	}
+
+	for (int x = 0; x <= smax; x++) {
+		for (int y = 0; y <= smax; y++) {
+			if (!inits[x][y]) {
+				m[{x, y}] = -1;
+			}
+		}
+	}
+
+	rec({0, 0}, 0);
+	cout << m[{smax, smax}] << '\n';
+}