2023 day 10

2023/10/main-1.cpp

@@ -0,0 +1,96 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<string> lines;
+
+#define R(x, y) rets.push_back(make_pair(r + x, c + y))
+vector<pair<int, int>> findcons(int r, int c) {
+	vector<pair<int, int>> rets;
+	switch (lines[r][c]) {
+	case '|':
+		R(-1, 0);
+		R(1, 0);
+		break;
+	case '-':
+		R(0, -1);
+		R(0, 1);
+		break;
+	case 'L':
+		R(-1, 0);
+		R(0, 1);
+		break;
+	case 'J':
+		R(-1, 0);
+		R(0, -1);
+		break;
+	case '7':
+		R(1, 0);
+		R(0, -1);
+		break;
+	case 'F':
+		R(1, 0);
+		R(0, 1);
+		break;
+	case 'S':
+		for (int rr = -1; rr <= 1; rr++) {
+			for (int cc = -1; cc <= 1; cc++) {
+				if (rr == 0 && cc == 0)
+					continue;
+				unsigned int rrr = r + rr, ccc = c + cc;
+				if ((int)rrr < 0 || rrr == lines.size() || (int)ccc < 0 || ccc == lines[rrr].size())
+					continue;
+				for (auto& con : findcons(rrr, ccc)) {
+					if (con.first == r && con.second == c) {
+						R(rr, cc);
+						goto lend;
+					}
+				}
+			}
+		}
+	lend:
+		break;
+	}
+	return rets;
+}
+#undef R
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	string line;
+
+	while (getline(cin, line) && !line.empty()) {
+		lines.push_back(line);
+	}
+
+	int sr = 0, sc = 0;
+	for (unsigned int rr = 0; rr < lines.size(); rr++) {
+		for (unsigned int cc = 0; cc < lines[rr].size(); cc++) {
+			if (lines[rr][cc] == 'S') {
+				sr = rr;
+				sc = cc;
+				goto lend;
+			}
+		}
+	}
+lend:
+	const auto& scons = findcons(sr, sc);
+	int lr = sr, lc = sc, r = scons[0].first, c = scons[0].second;
+	int ret = 1;
+
+	do {
+		for (auto& con : findcons(r, c)) {
+			if (con.first == lr && con.second == lc)
+				continue;
+			lr = r;
+			lc = c;
+			r = con.first;
+			c = con.second;
+			ret++;
+			break;
+		}
+	} while (r != sr || c != sc);
+
+	cout << ret / 2 << '\n';
+}

2023/10/main-2.cpp

@@ -0,0 +1,151 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<string> lines;
+
+#define R(x, y) rets.push_back(make_pair(r + x, c + y))
+vector<pair<int, int>> findcons(int r, int c) {
+	vector<pair<int, int>> rets;
+	switch (lines[r][c]) {
+	case '|':
+		R(-1, 0);
+		R(1, 0);
+		break;
+	case '-':
+		R(0, -1);
+		R(0, 1);
+		break;
+	case 'L':
+		R(-1, 0);
+		R(0, 1);
+		break;
+	case 'J':
+		R(-1, 0);
+		R(0, -1);
+		break;
+	case '7':
+		R(1, 0);
+		R(0, -1);
+		break;
+	case 'F':
+		R(1, 0);
+		R(0, 1);
+		break;
+	case 'S':
+		for (int rr = -1; rr <= 1; rr++) {
+			for (int cc = -1; cc <= 1; cc++) {
+				if (rr == 0 && cc == 0)
+					continue;
+				unsigned int rrr = r + rr, ccc = c + cc;
+				if ((int)rrr < 0 || rrr == lines.size() || (int)ccc < 0 || ccc == lines[rrr].size())
+					continue;
+				for (auto& con : findcons(rrr, ccc)) {
+					if (con.first == r && con.second == c) {
+						R(rr, cc);
+						goto lend;
+					}
+				}
+			}
+		}
+	lend:
+		break;
+	}
+	return rets;
+}
+#undef R
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	string line;
+
+	while (getline(cin, line) && !line.empty()) {
+		lines.push_back(line);
+	}
+
+	int sr = 0, sc = 0;
+	for (unsigned int rr = 0; rr < lines.size(); rr++) {
+		for (unsigned int cc = 0; cc < lines[rr].size(); cc++) {
+			if (lines[rr][cc] == 'S') {
+				sr = rr;
+				sc = cc;
+				goto lend;
+			}
+		}
+	}
+lend:
+	const auto& scons = findcons(sr, sc);
+	int lr = sr, lc = sc, r = scons[0].first, c = scons[0].second;
+
+	bool path[lines.size()][lines[0].size()];
+	memset(path, 0, lines.size() * lines[0].size() * sizeof(bool));
+	path[r][c] = true;
+	bool others[3][3] = {};
+	others[r - sr + 1][c - sc + 1] = true;
+
+	do {
+		for (auto& con : findcons(r, c)) {
+			if (con.first == lr && con.second == lc)
+				continue;
+			lr = r;
+			lc = c;
+			r = con.first;
+			c = con.second;
+			path[r][c] = true;
+			break;
+		}
+	} while (r != sr || c != sc);
+	others[lr - sr + 1][lc - sc + 1] = true;
+
+	int ret = 0;
+
+	for (unsigned int r = 0; r < lines.size(); r++) {
+		bool inside = false, realinside = false;
+		char le = '\0';
+		for (unsigned int c = 0; c < lines[r].size(); c++) {
+			if (path[r][c]) {
+				char ch = lines[r][c];
+			sstart:
+				switch (ch) {
+				case 'S':
+					if (others[1][2]) {
+						if (others[1][0])
+							break;
+						if (others[0][1]) {
+							ch = 'L';
+						} else {
+							ch = 'F';
+						}
+					} else if (others[1][0]) {
+						if (others[0][1]) {
+							ch = 'J';
+						} else {
+							ch = '7';
+						}
+					} else {
+						ch = '|';
+					}
+					goto sstart;
+				case 'L':
+				case 'F':
+					le = ch;
+					break;
+				case 'J':
+				case '7':
+					if ((le == 'L' && ch == 'J') || (le == 'F' && ch == '7'))
+						break;
+					// fallthrough
+				case '|':
+					inside = !inside;
+					realinside = inside && !realinside;
+					break;
+				}
+			} else if (realinside) {
+				ret++;
+			}
+		}
+	}
+
+	cout << ret << '\n';
+}