1 files changed, 110 insertions, 0 deletions
diff --git a/day_02.zig b/day_02.zig
new file mode 100644
index 0000000..ce5e165
--- /dev/null
+++ b/day_02.zig
@@ -0,0 +1,110 @@
+const std = @import("std");
+const Result = @import("util/aoc.zig").Result;
+
+const Hand = enum(u8) { Rock = 1, Paper = 2, Scissors = 3 };
+const Outcome = enum(u8) { Win = 6, Draw = 3, Lose = 0 };
+
+const KV_Hand = struct { @"0": []const u8, @"1": Hand };
+const KV_Outcome = struct { @"0": []const u8, @"1": Outcome };
+
+const Player_A_KV = std.ComptimeStringMap(Hand, [_]KV_Hand{
+    .{ .@"0" = "A", .@"1" = .Rock },
+    .{ .@"0" = "B", .@"1" = .Paper },
+    .{ .@"0" = "C", .@"1" = .Scissors },
+});
+
+const Player_B_KV = std.ComptimeStringMap(Hand, [_]KV_Hand{
+    .{ .@"0" = "X", .@"1" = .Rock },
+    .{ .@"0" = "Y", .@"1" = .Paper },
+    .{ .@"0" = "Z", .@"1" = .Scissors },
+});
+
+const Outcome_KV = std.ComptimeStringMap(Outcome, [_]KV_Outcome{
+    .{ .@"0" = "X", .@"1" = .Lose },
+    .{ .@"0" = "Y", .@"1" = .Draw },
+    .{ .@"0" = "Z", .@"1" = .Win },
+});
+
+const match_impl = struct {
+    fn puzzle_1(a: Hand, b: Hand) u8 {
+        switch (b) {
+            .Rock => {
+                switch (a) {
+                    .Rock => return @enumToInt(b) + @enumToInt(Outcome.Draw),
+                    .Paper => return @enumToInt(b) + @enumToInt(Outcome.Lose),
+                    .Scissors => return @enumToInt(b) + @enumToInt(Outcome.Win),
+                }
+            },
+            .Paper => {
+                switch (a) {
+                    .Rock => return @enumToInt(b) + @enumToInt(Outcome.Win),
+                    .Paper => return @enumToInt(b) + @enumToInt(Outcome.Draw),
+                    .Scissors => return @enumToInt(b) + @enumToInt(Outcome.Lose),
+                }
+            },
+            .Scissors => {
+                switch (a) {
+                    .Rock => return @enumToInt(b) + @enumToInt(Outcome.Lose),
+                    .Paper => return @enumToInt(b) + @enumToInt(Outcome.Win),
+                    .Scissors => return @enumToInt(b) + @enumToInt(Outcome.Draw),
+                }
+            },
+        }
+    }
+
+    fn puzzle_2(a: Hand, b: Outcome) u8 {
+        switch (a) {
+            .Rock => {
+                switch (b) {
+                    .Win => return @enumToInt(b) + @enumToInt(Hand.Paper),
+                    .Lose => return @enumToInt(b) + @enumToInt(Hand.Scissors),
+                    .Draw => return @enumToInt(b) + @enumToInt(Hand.Rock),
+                }
+            },
+            .Paper => {
+                switch (b) {
+                    .Win => return @enumToInt(b) + @enumToInt(Hand.Scissors),
+                    .Lose => return @enumToInt(b) + @enumToInt(Hand.Rock),
+                    .Draw => return @enumToInt(b) + @enumToInt(Hand.Paper),
+                }
+            },
+            .Scissors => {
+                switch (b) {
+                    .Win => return @enumToInt(b) + @enumToInt(Hand.Rock),
+                    .Lose => return @enumToInt(b) + @enumToInt(Hand.Paper),
+                    .Draw => return @enumToInt(b) + @enumToInt(Hand.Scissors),
+                }
+            },
+        }
+    }
+};
+
+pub fn puzzle_1(input: []const u8) Result {
+    var iter = std.mem.split(u8, input, "\n");
+
+    var score: u16 = 0;
+
+    while (iter.next()) |line| {
+        score += match_impl.puzzle_1(
+            Player_A_KV.get(&[_]u8{line[0]}).?,
+            Player_B_KV.get(&[_]u8{line[2]}).?,
+        );
+    }
+
+    return .{ .int = score };
+}
+
+pub fn puzzle_2(input: []const u8) Result {
+    var iter = std.mem.split(u8, input, "\n");
+
+    var score: u16 = 0;
+
+    while (iter.next()) |line| {
+        score += match_impl.puzzle_2(
+            Player_A_KV.get(&[_]u8{line[0]}).?,
+            Outcome_KV.get(&[_]u8{line[2]}).?,
+        );
+    }
+
+    return .{ .int = score };
+}