day 2

day2_p1.zig

@@ -0,0 +1,32 @@
+const std = @import("std");
+
+pub fn main() !void {
+    const stdin = std.io.getStdIn();
+    var buf_io = std.io.bufferedReader(stdin.reader());
+    var reader = buf_io.reader();
+
+    var buf = [_]u8{0} ** 1024;
+    var total: usize = 0;
+    while (try reader.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        const trimmed = std.mem.trim(u8, line, "\n\r");
+        var it = std.mem.splitScalar(u8, trimmed, 'x');
+        const l = try std.fmt.parseInt(u32, it.first(), 10);
+        const w = try std.fmt.parseInt(u32, it.next().?, 10);
+        const h = try std.fmt.parseInt(u32, it.next().?, 10);
+        total += calculate_sqft(l, w, h);
+    }
+
+    std.debug.print("{}", .{total});
+}
+
+fn calculate_sqft(l: u32, w: u32, h: u32) u32 {
+    const coverage = 2 * l * w + 2 * w * h + 2 * h * l;
+    const paper = @min(l * w, w * h, h * l);
+
+    return coverage + paper;
+}
+
+test "day-test" {
+    try std.testing.expectEqual(calculate_sqft(2, 3, 4), 58);
+    try std.testing.expectEqual(calculate_sqft(1, 1, 10), 43);
+}

day2_p2.zig

@@ -0,0 +1,33 @@
+const std = @import("std");
+
+pub fn main() !void {
+    const stdin = std.io.getStdIn();
+    var buf_io = std.io.bufferedReader(stdin.reader());
+    var reader = buf_io.reader();
+
+    var buf = [_]u8{0} ** 1024;
+    var total: usize = 0;
+    while (try reader.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        const trimmed = std.mem.trim(u8, line, "\n\r");
+        var it = std.mem.splitScalar(u8, trimmed, 'x');
+        const l = try std.fmt.parseInt(u32, it.first(), 10);
+        const w = try std.fmt.parseInt(u32, it.next().?, 10);
+        const h = try std.fmt.parseInt(u32, it.next().?, 10);
+        total += calculate_ribbon(l, w, h);
+    }
+
+    std.debug.print("{}", .{total});
+}
+
+fn calculate_ribbon(l: u32, w: u32, h: u32) u32 {
+    const wrapL = l + l + w + w;
+    const wrapW = w + w + h + h;
+    const wrapH = l + l + h + h;
+
+    return @min(wrapL, wrapW, wrapH) + l * w * h;
+}
+
+test "day-test" {
+    try std.testing.expectEqual(calculate_ribbon(2, 3, 4), 34);
+    try std.testing.expectEqual(calculate_ribbon(1, 1, 10), 14);
+}