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const std = @import("std");
const Result = @import("util/aoc.zig").Result;
pub fn puzzle_1(input: []const u8) Result {
var grid = std.mem.zeroes([99][99]u8);
load_grid(&grid, input);
var count: i32 = 0;
for (grid) |_, y| {
for (grid[y]) |_, x| {
const position = [_]usize{ y, x };
if (is_visible_left(position, grid) or
is_visible_right(position, grid) or is_visible_up(position, grid) or
is_visible_down(position, grid)) count += 1;
}
}
return .{ .int = count };
}
pub fn puzzle_2(input: []const u8) Result {
var grid = std.mem.zeroes([99][99]u8);
load_grid(&grid, input);
var max: u32 = 0;
for (grid) |_, y| {
for (grid[y]) |_, x| {
const position = [_]usize{ y, x };
const down = view_distance_down(position, grid);
const left = view_distance_left(position, grid);
const right = view_distance_right(position, grid);
const up = view_distance_up(position, grid);
const n: u32 = down * up * left * right;
max = std.math.max(n, max);
}
}
return .{ .int = @intCast(i32, max) };
}
fn load_grid(grid: *[99][99]u8, input: []const u8) void {
var iter = std.mem.split(u8, input, "\n");
var row_idx: usize = 0;
while (iter.next()) |line| : (row_idx += 1) {
for (line) |char, column| {
grid[row_idx][column] = std.fmt.parseInt(u8, &[_]u8{char}, 0) catch unreachable;
}
}
}
fn is_visible_down(pos: [2]usize, grid: [99][99]u8) bool {
var max = grid[pos[0]][pos[1]];
var i = pos[0] + 1;
for (grid[i..]) |_| {
if (grid[i][pos[1]] >= max) return false;
i += 1;
}
return true;
}
fn is_visible_up(pos: [2]usize, grid: [99][99]u8) bool {
var max = grid[pos[0]][pos[1]];
for (grid[0..pos[0]]) |row| if (row[pos[1]] >= max) return false;
return true;
}
fn is_visible_right(pos: [2]usize, grid: [99][99]u8) bool {
var max = grid[pos[0]][pos[1]];
for (grid[pos[0]][pos[1] + 1 ..]) |n| if (n >= max) return false;
return true;
}
fn is_visible_left(pos: [2]usize, grid: [99][99]u8) bool {
var max = grid[pos[0]][pos[1]];
for (grid[pos[0]][0..pos[1]]) |n| if (n >= max) return false;
return true;
}
fn view_distance_down(pos: [2]usize, grid: [99][99]u8) u32 {
var max = grid[pos[0]][pos[1]];
var treecount: u8 = 0;
var i = pos[0] + 1;
for (grid[i..]) |_| {
if (grid[i][pos[1]] >= max) return treecount + 1;
treecount += 1;
i += 1;
}
return treecount;
}
fn view_distance_right(pos: [2]usize, grid: [99][99]u8) u32 {
var max = grid[pos[0]][pos[1]];
var treecount: u8 = 0;
for (grid[pos[0]][pos[1] + 1 ..]) |n| {
if (n >= max) return treecount + 1;
treecount += 1;
}
return treecount;
}
fn view_distance_up(pos: [2]usize, grid: [99][99]u8) u32 {
var max = grid[pos[0]][pos[1]];
var treecount: u8 = 0;
var i: usize = pos[0];
while (i > 0) : (treecount += 1) {
i -= 1;
if (grid[i][pos[1]] >= max) return treecount + 1;
}
return treecount;
}
fn view_distance_left(pos: [2]usize, grid: [99][99]u8) u32 {
var max = grid[pos[0]][pos[1]];
var treecount: u8 = 0;
var i: usize = pos[1];
while (i > 0) : (treecount += 1) {
i -= 1;
if (grid[pos[0]][i] >= max) return treecount + 1;
}
return treecount;
}
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