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const std = @import("std");
const mecha = @import("mecha");
const print = std.debug.print;
pub fn solve(part: []u8, buffer: []u8, allocator: std.mem.Allocator) !void {
if (std.mem.eql(u8, part, "1")) {
try part1(buffer, allocator);
} else {
try part2(buffer, allocator);
}
}
fn dfs(grid: []const []const usize, row: i32, col: i32, previous: i32, seen: [][]bool) !i32 {
if (row >= 0 and row < grid.len and col >= 0 and col < grid.len and !seen[@intCast(row)][@intCast(col)]) {
const value = grid[@intCast(row)][@intCast(col)];
if (previous + 1 != value) return 0;
seen[@intCast(row)][@intCast(col)] = true;
if (value == 9) {
return 1;
}
var out: i32 = 0;
out += try dfs(grid, row + 1, col, @intCast(value), seen);
out += try dfs(grid, row - 1, col, @intCast(value), seen);
out += try dfs(grid, row, col + 1, @intCast(value), seen);
out += try dfs(grid, row, col - 1, @intCast(value), seen);
return out;
} else {
return 0;
}
}
fn part1(buffer: []const u8, allocator: std.mem.Allocator) !void {
var lines = std.mem.splitScalar(u8, buffer, '\n');
const width = lines.next().?.len;
lines.reset();
var grid: [][]usize = try allocator.alloc([]usize, width);
defer allocator.free(grid);
for (0..width) |i| {
grid[i] = try allocator.alloc(usize, width);
@memset(grid[i], 0);
}
var row: usize = 0;
while (lines.next()) |line| {
if (line.len == 0) break;
for (line, 0..) |item, col| {
if (item == '.') {
grid[row][col] = 15;
} else {
grid[row][col] = item - '0';
}
}
row += 1;
}
var out: i32 = 0;
for (0..width) |r| {
for (0..width) |c| {
if (grid[r][c] == 0) {
var seen: [][]bool = try allocator.alloc([]bool, width);
defer allocator.free(seen);
for (0..width) |i| {
seen[i] = try allocator.alloc(bool, width);
@memset(seen[i], false);
}
out += try dfs(grid, @intCast(r), @intCast(c), -1, seen);
for (0..width) |i| {
allocator.free(seen[i]);
}
}
}
}
for (0..width) |i| {
allocator.free(grid[i]);
}
print("{d}\n", .{out});
}
//-------------------------PART2-----------------------------------------
fn dfs2(lookup: [][]i32, grid: []const []const usize, row: i32, col: i32, previous: i32) !i32 {
if (row >= 0 and row < grid.len and col >= 0 and col < grid.len) {
const value = grid[@intCast(row)][@intCast(col)];
const look = lookup[@intCast(row)][@intCast(col)];
if (previous + 1 != value) return 0;
if (look > 0) return look;
if (value == 9) {
return 1;
}
lookup[@intCast(row)][@intCast(col)] += try dfs2(lookup, grid, row + 1, col, @intCast(value));
lookup[@intCast(row)][@intCast(col)] += try dfs2(lookup, grid, row - 1, col, @intCast(value));
lookup[@intCast(row)][@intCast(col)] += try dfs2(lookup, grid, row, col + 1, @intCast(value));
lookup[@intCast(row)][@intCast(col)] += try dfs2(lookup, grid, row, col - 1, @intCast(value));
return lookup[@intCast(row)][@intCast(col)];
} else {
return 0;
}
}
fn part2(buffer: []const u8, allocator: std.mem.Allocator) !void {
var lines = std.mem.splitScalar(u8, buffer, '\n');
const width = lines.next().?.len;
lines.reset();
var grid: [][]usize = try allocator.alloc([]usize, width);
defer allocator.free(grid);
for (0..width) |i| {
grid[i] = try allocator.alloc(usize, width);
@memset(grid[i], 0);
}
var row: usize = 0;
while (lines.next()) |line| {
if (line.len == 0) break;
for (line, 0..) |item, col| {
if (item == '.') {
grid[row][col] = 15;
} else {
grid[row][col] = item - '0';
}
}
row += 1;
}
var out: i32 = 0;
const lookup: [][]i32 = try allocator.alloc([]i32, width);
for (0..width) |i| {
lookup[i] = try allocator.alloc(i32, width);
}
defer allocator.free(lookup);
for (0..width) |r| {
for (0..width) |c| {
if (grid[r][c] == 0) {
out += try dfs2(
lookup,
grid,
@intCast(r),
@intCast(c),
-1,
);
}
}
}
for (0..width) |i| {
allocator.free(lookup[i]);
allocator.free(grid[i]);
}
print("{d}\n", .{out});
}
|
