Finish day07, part 1

src/days/day07.zig

@@ -1,7 +1,86 @@
 const std = @import("std");
 
-pub const title = "Day 07";
+pub const title = "Day 07: Laboratories";
 
-pub fn run(_: std.mem.Allocator) !void {
+pub fn run(allocator: std.mem.Allocator) !void {
+    const input = @embedFile("./input/day07.txt");
+    //const input =
+    //    \\.......S.......
+    //    \\...............
+    //    \\.......^.......
+    //    \\...............
+    //    \\......^.^......
+    //    \\...............
+    //    \\.....^.^.^.....
+    //    \\...............
+    //    \\....^.^...^....
+    //    \\...............
+    //    \\...^.^...^.^...
+    //    \\...............
+    //    \\..^...^.....^..
+    //    \\...............
+    //    \\.^.^.^.^.^...^.
+    //    \\...............
+    //    ;
+
+    var lines = std.mem.tokenizeScalar(u8, input, '\n');
+
+    const first_line = lines.next() orelse unreachable;
+    const starting_position = for (first_line, 0..) |c, i| {
+        if (c == 'S') break i;
+    } else unreachable;
+    const line_len = first_line.len;
+
+    std.debug.print("starting_position = {d}\n", .{starting_position});
+
+    std.debug.print("{s}\n", .{first_line});
+
+    const previous_line = try allocator.alloc(u8, line_len);
+    defer allocator.free(previous_line);
+
+    var accumulator: usize = 0;
+
+    var i: usize = 0;
+    while (lines.next()) |line| {
+        defer i += 1;
+
+        const current_line = try allocator.alloc(u8, line_len);
+        defer allocator.free(current_line);
+        @memcpy(current_line, line);
+
+        defer @memcpy(previous_line, current_line);
+
+        defer std.debug.print("{s}\n", .{current_line});
+
+        if (i == 0) {
+            std.debug.assert(current_line[starting_position] == '.');
+            current_line[starting_position] = '|';
+            continue;
+        }
+
+        for (line, 0..) |c, ci| {
+            if (previous_line[ci] == '|') {
+                if (c == '.') {
+                    current_line[ci] = '|';
+                } else if (c == '^') {
+                    accumulator += 1;
+                    if (ci != 0 and current_line[ci - 1] == '.') {
+                        current_line[ci - 1] = '|';
+                    }
+                    if (ci != line_len - 1 and current_line[ci + 1] == '.') {
+                        current_line[ci + 1] = '|';
+                    }
+                }
+            }
+        }
+    }
+
+    var buffer: [8]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    const stdout = &stdout_writer.interface;
+
+    try stdout.print("{d}\n", .{accumulator});
+
+    try stdout.flush();
 }