27 lines
989 B
Zig
27 lines
989 B
Zig
const std = @import("std");
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const input = @embedFile("input");
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const MAP_SIZE = 60;
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pub fn main() !void {
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var map = [_][MAP_SIZE + 2]u8{[_]u8{0} ** (MAP_SIZE + 2)} ** (MAP_SIZE + 2);
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for (input, 0..) |c, i| {
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if (c == '\n') continue;
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map[@divFloor(i, MAP_SIZE + 1) + 1][i % (MAP_SIZE + 1) + 1] = c - '0';
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}
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var total: usize = 0;
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for (1..MAP_SIZE + 1) |x| for (1..MAP_SIZE + 1) |y| if (map[x][y] == 0) try step(map, x, y, &total);
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try std.testing.expectEqual(1651, total);
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}
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fn step(map: [MAP_SIZE + 2][MAP_SIZE + 2]u8, x: usize, y: usize, total: *usize) !void {
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const height = map[x][y];
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if (height == 9) total.* += 1;
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if (map[x - 1][y] == (height + 1)) try step(map, x - 1, y, total); // Up
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if (map[x + 1][y] == (height + 1)) try step(map, x + 1, y, total); // Down
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if (map[x][y - 1] == (height + 1)) try step(map, x, y - 1, total); // Left
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if (map[x][y + 1] == (height + 1)) try step(map, x, y + 1, total); // Right
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}
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