1 files changed, 91 insertions, 0 deletions
diff --git a/src/day02.zig b/src/day02.zig
new file mode 100644
index 0000000..cad2d9d
--- /dev/null
+++ b/src/day02.zig
@@ -0,0 +1,91 @@
+const std = @import("std");
+const stdin = std.io.getStdIn();
+const print = std.debug.print;
+
+pub fn solve(part: []u8, buffer: []u8) !void {
+    var lines = std.mem.splitScalar(u8, buffer, '\n');
+    if (std.mem.eql(u8, part, "part1")) {
+        try part1(&lines);
+    } else {
+        try part2(&lines);
+    }
+}
+
+fn part1(lines: *std.mem.SplitIterator(u8, .scalar)) !void {
+    var count: usize = 0;
+    lines: while (lines.next()) |line| {
+        if (line.len > 0) {
+            var components = std.mem.splitScalar(u8, line, ' ');
+            var previous: i32 = try std.fmt.parseInt(i32, components.next().?, 10);
+            var increasing: i32 = 0;
+            while (components.next()) |number_s| {
+                const number = try std.fmt.parseInt(i32, number_s, 10);
+                if (increasing == 0) {
+                    if (previous > number) {
+                        increasing = -1;
+                    } else {
+                        increasing = 1;
+                    }
+                }
+
+                const difference = (number - previous) * increasing;
+                if (difference < 1 or difference > 3) {
+                    continue :lines;
+                }
+                previous = number;
+            }
+            count += 1;
+        }
+    }
+
+    print("Safe count: {d}\n", .{count});
+}
+
+fn part2(lines: *std.mem.SplitIterator(u8, .scalar)) !void {
+    var count: usize = 0;
+    while (lines.next()) |line| {
+        if (line.len > 0) {
+            var components = std.mem.splitScalar(u8, line, ' ');
+
+            var i: usize = 0;
+            var j: usize = 0;
+
+            counter: while (i <= j) {
+                j = 0;
+                components.reset();
+
+                if (i == 0) {
+                    _ = components.next();
+                }
+
+                var previous: i32 = try std.fmt.parseInt(i32, components.next().?, 10);
+                var increasing: i32 = 0;
+                while (components.next()) |number_s| {
+                    if (i != j) {
+                        const number = try std.fmt.parseInt(i32, number_s, 10);
+                        if (increasing == 0) {
+                            if (previous > number) {
+                                increasing = -1;
+                            } else {
+                                increasing = 1;
+                            }
+                        }
+
+                        const difference = (number - previous) * increasing;
+                        if (difference < 1 or difference > 3) {
+                            i += 1;
+                            continue :counter;
+                        }
+                        previous = number;
+                    }
+
+                    j += 1;
+                }
+
+                count += 1;
+                break;
+            }
+        }
+    }
+    print("Safe count: {d}\n", .{count});
+}