2024 day 10

2024/10/main-1.cpp

@@ -0,0 +1,59 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	string line;
+	vector<vector<pair<int, set<int>>>> m;
+	int h = 0;
+	while (getline(cin, line) && !line.empty()) {
+		istringstream l(line);
+		char c;
+		vector<pair<int, set<int>>> mm;
+		while (l >> c) {
+			set<int> s;
+			if (c == '9') {
+				s.insert(h);
+			}
+			mm.push_back({c - '0', s});
+			h++;
+		}
+		m.push_back(mm);
+	}
+
+	int xm = m.size(), ym = m[0].size();
+
+	for (int i = 9; i > 0; i--) {
+		for (int x = 0; x < xm; x++) {
+			for (int y = 0; y < ym; y++) {
+				auto &[n, c] = m[x][y];
+				if (n != i) {
+					continue;
+				}
+				vector<pair<int, int>> xxyy = {
+					{x - 1, y}, {x + 1, y}, {x, y - 1}, {x, y + 1}};
+				for (auto &[xx, yy] : xxyy) {
+					if (xx < 0 || yy < 0 || xx >= xm || yy >= ym) {
+						continue;
+					}
+					auto &[nn, cc] = m[xx][yy];
+					if (nn == n - 1) {
+						cc.insert(c.begin(), c.end());
+					}
+				}
+			}
+		}
+	}
+
+	int sum = 0;
+	for (auto &mm : m) {
+		for (auto &[n, c] : mm) {
+			if (n == 0) {
+				sum += c.size();
+			}
+		}
+	}
+	cout << sum << '\n';
+}

2024/10/main-2.cpp

@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	string line;
+	vector<vector<pair<int, int>>> m;
+	while (getline(cin, line) && !line.empty()) {
+		istringstream l(line);
+		char c;
+		vector<pair<int, int>> mm;
+		while (l >> c) {
+			mm.push_back({c - '0', c == '9' ? 1 : 0});
+		}
+		m.push_back(mm);
+	}
+
+	int xm = m.size(), ym = m[0].size();
+
+	for (int i = 9; i > 0; i--) {
+		for (int x = 0; x < xm; x++) {
+			for (int y = 0; y < ym; y++) {
+				auto &[n, c] = m[x][y];
+				if (n != i) {
+					continue;
+				}
+				vector<pair<int, int>> xxyy = {
+					{x - 1, y}, {x + 1, y}, {x, y - 1}, {x, y + 1}};
+				for (auto &[xx, yy] : xxyy) {
+					if (xx < 0 || yy < 0 || xx >= xm || yy >= ym) {
+						continue;
+					}
+					auto &[nn, cc] = m[xx][yy];
+					if (nn == n - 1) {
+						cc += c;
+					}
+				}
+			}
+		}
+	}
+
+	int sum = 0;
+	for (auto &mm : m) {
+		for (auto &[n, c] : mm) {
+			if (n == 0) {
+				sum += c;
+			}
+		}
+	}
+	cout << sum << '\n';
+}