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day 4

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TheGeneralist 2024-12-04 19:31:04 +01:00
parent 5982a62d70
commit 1d9f361587
Signed by: thegeneralist01
SSH key fingerprint: SHA256:pp9qddbCNmVNoSjevdvQvM5z0DHN7LTa8qBMbcMq/R4
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day4/day4_part1.zig Normal file
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const std = @import("std");
const input = @embedFile("input");
const Coord = struct {
x: i32,
y: i32,
};
const Direction = struct {
x: i64,
y: i64,
const Left = Direction{ .x = -1, .y = 0 };
const Right = Direction{ .x = 1, .y = 0 };
const Up = Direction{ .x = 0, .y = -1 };
const Down = Direction{ .x = 0, .y = 1 };
const UpLeft = Direction{ .x = -1, .y = -1 };
const UpRight = Direction{ .x = 1, .y = -1 };
const DownLeft = Direction{ .x = -1, .y = 1 };
const DownRight = Direction{ .x = 1, .y = 1 };
};
fn xmas_exists(grid: [][]const u8, start_x: i64, start_y: i64, direction: Direction) bool {
const xmas = "XMAS";
var x = start_x;
var y = start_y;
for (xmas) |c| {
if (x < 0 or y < 0 or y >= grid.len or x >= grid[@intCast(y)].len) return false;
if (grid[@intCast(y)][@intCast(x)] != c) return false;
x += @intCast(direction.x);
y += @intCast(direction.y);
}
return true;
}
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
const ally = gpa.allocator();
defer _ = gpa.deinit();
var lines = std.mem.tokenize(u8, input, "\r\n");
var grid = std.ArrayList([]const u8).init(ally);
defer grid.deinit();
while (lines.next()) |line| {
if (line.len > 0) {
try grid.append(line);
}
}
var xmas: u16 = 0;
for (grid.items, 0..) |row, y| {
for (row, 0..) |_, x| {
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.Left)) xmas += 1;
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.Right)) xmas += 1;
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.Up)) xmas += 1;
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.Down)) xmas += 1;
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.UpLeft)) xmas += 1;
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.UpRight)) xmas += 1;
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.DownLeft)) xmas += 1;
if (xmas_exists(grid.items, @intCast(x), @intCast(y), Direction.DownRight)) xmas += 1;
}
}
std.debug.print("XMAS count: {}\n", .{xmas});
}