Day 1

1 files changed, 139 insertions, 0 deletions

diff --git a/day1.zig b/day1.zig
new file mode 100644
index 0000000..ed6d7e9
--- /dev/null
+++ b/day1.zig
@@ -0,0 +1,139 @@
+const std = @import("std");
+const digits = "0123456789";
+
+const words = [_][]const u8{
+    "0",
+    "1",
+    "2",
+    "3",
+    "4",
+    "5",
+    "6",
+    "7",
+    "8",
+    "9",
+    "zero",
+    "one",
+    "two",
+    "three",
+    "four",
+    "five",
+    "six",
+    "seven",
+    "eight",
+    "nine",
+    "ten",
+};
+const w2d = std.comptime_string_map.ComptimeStringMap(u8, .{
+    .{ "0", 0 },
+    .{ "1", 1 },
+    .{ "2", 2 },
+    .{ "3", 3 },
+    .{ "4", 4 },
+    .{ "5", 5 },
+    .{ "6", 6 },
+    .{ "7", 7 },
+    .{ "8", 8 },
+    .{ "9", 9 },
+    .{ "zero", 0 },
+    .{ "one", 1 },
+    .{ "two", 2 },
+    .{ "three", 3 },
+    .{ "four", 4 },
+    .{ "five", 5 },
+    .{ "six", 6 },
+    .{ "seven", 7 },
+    .{ "eight", 8 },
+    .{ "nine", 9 },
+});
+
+const Input = struct {
+    const Part = enum { pt1, pt2 };
+    file: []const u8,
+    part: Part,
+};
+
+pub fn getInput() !Input {
+    var p = std.process.args();
+    var in: Input = .{
+        .file = "",
+        .part = .pt1,
+    };
+    if (!p.skip()) return error.NoProgramName;
+    if (p.next()) |pp| {
+        if (std.mem.eql(u8, pp, "pt1")) {
+            in.part = .pt1;
+        } else if (std.mem.eql(u8, pp, "pt2")) {
+            in.part = .pt2;
+        } else {
+            return error.BadPartSpecified;
+        }
+    } else {
+        return error.NoPartSpecified;
+    }
+    if (p.next()) |pp| {
+        in.file = pp;
+    } else {
+        return error.NoPartSpecified;
+    }
+    return in;
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const a = gpa.allocator();
+    const in = try getInput();
+    var f = try std.fs.cwd().openFile(in.file, .{});
+    defer f.close();
+    var c = try f.readToEndAlloc(a, std.math.maxInt(u32));
+    defer a.free(c);
+    var l = std.mem.splitScalar(u8, c, '\n');
+    var t: u64 = 0;
+    while (l.next()) |n| {
+        switch (in.part) {
+            .pt1 => {
+                const ix1 = std.mem.indexOfAny(u8, n, digits) orelse return error.NoDigits;
+                const ix2 = std.mem.lastIndexOfAny(u8, n, digits) orelse return error.NoDigits;
+                const v1 = n[ix1] - '0'; // ascii -> number
+                const v2 = n[ix2] - '0';
+                const x = 10 * v1 + v2;
+                t += x;
+            },
+            .pt2 => {
+                var ix1: ?usize = null;
+                var v1: u8 = 0;
+                var ix2: ?usize = null;
+                var v2: u8 = 0;
+                for (words) |word| {
+                    if (std.mem.indexOf(u8, n, word)) |mix1| {
+                        if (ix1) |rix1| {
+                            if (mix1 < rix1) {
+                                ix1 = mix1;
+                                v1 = w2d.get(word) orelse return error.Wtf;
+                            }
+                        } else {
+                            ix1 = mix1;
+                            v1 = w2d.get(word) orelse return error.Wtf;
+                        }
+                    }
+                    if (std.mem.lastIndexOf(u8, n, word)) |mix2| {
+                        if (ix2) |rix2| {
+                            if (mix2 > rix2) {
+                                ix2 = mix2;
+                                v2 = w2d.get(word) orelse return error.Wtf;
+                            }
+                        } else {
+                            ix2 = mix2;
+                            v2 = w2d.get(word) orelse return error.Wtf;
+                        }
+                    }
+                }
+                //std.log.warn("n {s} v1 {} v2 {}", .{ n, v1, v2 });
+                if (ix1 == null or ix2 == null) return error.NoDigits;
+                t += (10 * v1) + v2;
+            },
+        }
+    }
+    try std.fmt.format(std.io.getStdOut().writer(), "sum of calibration values: {}\n", .{t});
+}