2015: Day 1 complete

2015/day1.zig

@@ -0,0 +1,55 @@
+const std = @import("std");
+
+fn part1(directions: std.ArrayList(u8), floor: *i16) void {
+    for (directions.items) |direction| {
+        if (direction == '(') {
+            floor.* += 1;
+        } else if (direction == ')') {
+            floor.* -= 1;
+        }
+    }
+}
+
+fn part2(directions: std.ArrayList(u8), pos: *i16) void {
+    var floor: i16 = 0;
+    for (directions.items) |direction| {
+        if (direction == '(') {
+            floor += 1;
+        } else if (direction == ')') {
+            floor -= 1;
+        }
+        pos.* += 1;
+
+        if (floor == -1) break;
+    }
+}
+
+pub fn main() !void {
+    const file = try std.fs.cwd().openFile("day1.txt", .{});
+    defer file.close();
+
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    const alloc = arena.allocator();
+
+    var buf = std.io.bufferedReader(file.reader());
+
+    var directions = std.ArrayList(u8).init(alloc);
+    defer directions.deinit();
+
+    while (true) {
+        buf.reader().streamUntilDelimiter(directions.writer(), '\n', null) catch |err| switch (err) {
+            error.EndOfStream => break,
+            else => return err,
+        };
+    }
+
+    var floor: i16 = 0;
+    var position: i16 = 0;
+
+    part1(directions, &floor);
+    part2(directions, &position);
+
+    std.debug.print("Ending floor: {d}\n", .{floor});
+    std.debug.print("Position when first entering basement: {d}\n", .{position});
+}