day 17 part 1

1 files changed, 125 insertions, 0 deletions

diff --git a/22.17/main.cpp b/22.17/main.cpp
new file mode 100644
index 0000000..6a5c0cb
--- /dev/null
+++ b/22.17/main.cpp
@@ -0,0 +1,125 @@
+#include <cassert>
+#include <iostream>
+#include <vector>
+using namespace std;
+
+uint8_t shapes[5][4] = {
+	{
+		0,
+		0,
+		0,
+		0b00011110
+	},
+	{
+		0,
+		0b00001000,
+		0b00011100,
+		0b00001000,
+	},
+	{
+		0,
+		0b00000100,
+		0b00000100,
+		0b00011100,
+	},
+	{
+		0b00010000,
+		0b00010000,
+		0b00010000,
+		0b00010000,
+	},
+	{
+		0,
+		0,
+		0b00011000,
+		0b00011000,
+	},
+};
+
+uint8_t
+signedShift(uint8_t a, int b) {
+	if (0 < b) return a >> b;
+	else return a << -b;
+}
+
+bool
+collide(vector<uint8_t> const& map, int shapeID, int x, int y)
+{
+	auto &shape = shapes[shapeID];
+	// y increasing upwards
+	for (int i = 0; i < 4; i++) {
+		uint8_t line = shape[3 - i];
+		if (signedShift(signedShift(line, x) & 0x7F, -x) != line) // wall coll
+			return true;
+		line = signedShift(line, x);
+		if (!(y + i < map.size())) continue;
+		if (line & map[y + i]) return true;
+	}
+	return false;
+}
+
+void
+place(vector<uint8_t>& map, int shapeID, int x, int y)
+{
+	auto &shape = shapes[shapeID];
+	for (int i = 0; i < 4; i++) {
+		uint8_t line = signedShift(shape[3 - i], x);
+		if (line == 0) break;
+		if (!(y + i < map.size())) map.push_back(0);
+		map[y + i] |= line;
+	}
+}
+
+void
+vis(vector<uint8_t> const& map)
+{
+	char l[9] = {0};
+	for (int i = map.size() - 1; 0 <= i; i--) {
+		for (int j = 0; j < 8; j++) {
+			l[7 - j] = (map[i] & (1 << j)) ? '#' : '.';
+		}
+		cout << l << endl;
+	}
+	cout << endl;
+}
+
+int
+getWind(string const& s, int step)
+{
+	char c = s[step % s.size()];
+	if (c == '<') return -1;
+	if (c == '>') return 1;
+	cout << s << endl;
+	throw "bad input";
+}
+
+int
+main()
+{
+	string input;
+	getline(cin, input);
+
+	int step = 0;
+	vector<uint8_t> map;
+	map.push_back(0x7F);
+	for (int i = 0; i < 2022; i++) {
+		int shape = i % 5;
+		int x = 0;
+		int y = map.size() + 3;
+		for (;;) {
+			int wind;
+			wind = getWind(input, step++);
+			if (!collide(map, shape, x + wind, y)) {
+				x += wind;
+			}
+			// cout << x << "," << y << endl;
+			if (collide(map, shape, x, y - 1)) {
+				break;
+			}
+			y--;
+		}
+		place(map, shape, x, y);
+		// vis(map);
+	}
+	cout << map.size() - 1 << endl;
+}