2024 day 8

2024/8/main-1.cpp

@@ -0,0 +1,46 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	map<char, vector<pair<int, int>>> nodes;
+	string line;
+	vector<string> lines;
+	while (getline(cin, line) && !line.empty()) {
+		lines.push_back(line);
+	}
+
+	int mx = lines.size(), my = lines[0].size();
+
+	for (int x = 0; x < mx; x++) {
+		for (int y = 0; y < my; y++) {
+			char c = lines[x][y];
+			if (c != '.') {
+				nodes[c].push_back({x, y});
+			}
+		}
+	}
+
+	set<pair<int, int>> total;
+	for (auto &[c, poss] : nodes) {
+		for (int a = 1; a < poss.size(); a++) {
+			for (int b = 0; b < a; b++) {
+				vector<pair<int, int>> pos = {
+					{poss[b].first * 2 - poss[a].first,
+					 poss[b].second * 2 - poss[a].second},
+					{poss[a].first * 2 - poss[b].first,
+					 poss[a].second * 2 - poss[b].second}};
+				for (auto &x : pos) {
+					if (x.first >= 0 && x.first < mx && x.second >= 0 &&
+						x.second < my) {
+						total.insert(x);
+					}
+				}
+			}
+		}
+	}
+
+	cout << total.size() << '\n';
+}

2024/8/main-2.cpp

@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	map<char, vector<pair<int, int>>> nodes;
+	string line;
+	vector<string> lines;
+	while (getline(cin, line) && !line.empty()) {
+		lines.push_back(line);
+	}
+
+	int mx = lines.size(), my = lines[0].size();
+
+	for (int x = 0; x < mx; x++) {
+		for (int y = 0; y < my; y++) {
+			char c = lines[x][y];
+			if (c != '.') {
+				nodes[c].push_back({x, y});
+			}
+		}
+	}
+
+	set<pair<int, int>> total;
+	for (auto &[c, poss] : nodes) {
+		for (int a = 1; a < poss.size(); a++) {
+			for (int b = 0; b < a; b++) {
+				int dx = poss[a].first - poss[b].first;
+				int dy = poss[a].second - poss[b].second;
+				int x = poss[a].first, y = poss[a].second;
+				while (x >= 0 && x < mx && y >= 0 && y < my) {
+					x -= dx;
+					y -= dy;
+				}
+				for (;;) {
+					x += dx;
+					y += dy;
+					if (!(x >= 0 && x < mx && y >= 0 && y < my)) {
+						break;
+					}
+					total.insert({x, y});
+				}
+			}
+		}
+	}
+
+	cout << total.size() << '\n';
+}