Day 2 done, started working on improving build.zig

build.zig

@@ -11,9 +11,14 @@ pub fn build(b: *std.build.Builder) void {
     // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
     const mode = b.standardReleaseOptions();
 
-    const dayPath = "src/day1.zig";
 
-    const exe = b.addExecutable("advent_of_code", dayPath);
+    const days = [_]u8{1, 2};
+
+    for (days) |day| {
+        const dayPath = b.fmt("src/day{}.zig", .{day});
+        const dayName = b.fmt("day{}", .{day});
+
+        const exe = b.addExecutable(dayName, dayPath);
         exe.setTarget(target);
         exe.setBuildMode(mode);
         exe.install();
@@ -33,4 +38,5 @@ pub fn build(b: *std.build.Builder) void {
 
         const test_step = b.step("test", "Run unit tests");
         test_step.dependOn(&exe_tests.step);
+    }
 }

src/day1.zig

@@ -36,10 +36,3 @@ pub fn main() !void {
 
     std.debug.print("Total calories of the top three elves: {}\n", .{sum});
 }
-
-test "simple test" {
-    var list = std.ArrayList(i32).init(std.testing.allocator);
-    defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
-    try list.append(42);
-    try std.testing.expectEqual(@as(i32, 42), list.pop());
-}

src/day2.zig

@@ -0,0 +1,172 @@
+const std = @import("std");
+
+const Outcomes = enum(u16) {
+    Lost = 0,
+    Draw = 3,
+    Win = 6,
+    INVALID = 99,
+
+    pub fn from_guide(value: u8) Outcomes{
+        return switch(value) {
+            'X' => Outcomes.Lost,
+            'Y' => Outcomes.Draw,
+            'Z' => Outcomes.Win,
+            else => Outcomes.INVALID,
+        };
+    }
+};
+
+const RPSStates = enum(i8) {
+    Rock = 0,
+    Paper =1,
+    Scissors = 2,
+    INVALID = 99,
+    _,
+
+    pub fn from_opponent(value: u8) RPSStates {
+        return switch(value) {
+            'A' => RPSStates.Rock, 
+            'B' => RPSStates.Paper,
+            'C' => RPSStates.Scissors,
+            else => RPSStates.INVALID
+        };
+    }
+
+    pub fn from_me(value: u8) RPSStates {
+        return switch(value) {
+            'X' => RPSStates.Rock, 
+            'Y' => RPSStates.Paper,
+            'Z' => RPSStates.Scissors,
+            else => RPSStates.INVALID
+        };
+    }
+
+
+    pub fn get_move_needed(outcome_needed: Outcomes, opp_choice: RPSStates) RPSStates {
+        return switch(outcome_needed) {
+            .Lost => opp_choice.get_strong_to_move(),
+            .Draw => opp_choice,
+            .Win => opp_choice.get_weak_to_move(),
+            else => unreachable
+        };
+    }
+
+    pub fn outcome(self: RPSStates, opp_choice: RPSStates) Outcomes {
+        if (self == opp_choice) {
+            return Outcomes.Draw;
+        }
+        else {
+            if (self.get_strong_to_move() == opp_choice) {
+                return Outcomes.Win;
+            }
+            else {
+                return Outcomes.Lost;
+            }
+        }
+    }
+
+    pub fn score_round(self: RPSStates, opp_choice: RPSStates) u16 {
+        var score: u16 = switch(self) {
+            .Rock => 1,
+            .Paper => 2,
+            .Scissors => 3,
+            else => unreachable
+        };
+
+        score += @enumToInt(self.outcome(opp_choice));
+
+        return score;
+    }
+
+    pub fn get_weak_to_move(self: RPSStates) RPSStates {
+        return @intToEnum(RPSStates, @mod((@enumToInt(self) + 1), 3));
+    }
+
+    pub fn get_strong_to_move(self: RPSStates) RPSStates {
+        return @intToEnum(RPSStates, @mod((@enumToInt(self) - 1), 3));
+    }
+};
+
+pub fn part1(opp_letter: u8, my_letter: u8) u16 {
+    const opp_choice = RPSStates.from_opponent(opp_letter);
+    const my_choice = RPSStates.from_me(my_letter);
+
+    return my_choice.score_round(opp_choice);
+}
+
+pub fn part2(opp_letter: u8, my_letter: u8) u16 {
+    const opp_choice = RPSStates.from_opponent(opp_letter);
+
+    const win_cond = Outcomes.from_guide(my_letter);
+    const my_choice = RPSStates.get_move_needed(win_cond, opp_choice);
+
+    return my_choice.score_round(opp_choice);
+}
+
+pub fn main() !void {
+    var file = try std.fs.cwd().openFile("inputs/day2.txt", .{});
+    defer file.close();
+
+    var buf_reader = std.io.bufferedReader(file.reader());
+    var in_stream = buf_reader.reader();
+
+    var buf: [1024]u8 = undefined;
+    var score_part1: u16 = 0;
+    var score_part2: u16 = 0;
+    while (try in_stream.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        const opp_letter: u8 = line[0];
+        const my_letter: u8 = line[2];
+
+
+        score_part1 += part1(opp_letter, my_letter);
+        score_part2 += part2(opp_letter, my_letter);
+    }
+
+    std.debug.print("PART1: My total score: {}\n", .{score_part1});
+    std.debug.print("PART2: My total score: {}\n", .{score_part2});
+}
+
+test "Win Conditions" {
+    var opp = RPSStates.Paper;
+    var me = RPSStates.Rock;
+
+    var score = me.score_round(opp);
+
+    try std.testing.expect(score == 1);
+
+    opp = RPSStates.Scissors;
+    me = RPSStates.Paper;
+
+    score = me.score_round(opp);
+
+    try std.testing.expect(score == 2);
+
+    opp = RPSStates.Rock;
+    me = RPSStates.Scissors;
+
+    score = me.score_round(opp);
+
+    try std.testing.expect(score == 3);
+
+    opp = RPSStates.Rock;
+    me = RPSStates.Paper;
+
+    score = me.score_round(opp);
+
+    try std.testing.expect(me.outcome(opp) == Outcomes.Win);
+    try std.testing.expect(score == 8);
+
+    opp = RPSStates.Paper;
+    me = RPSStates.Scissors;
+
+    score = me.score_round(opp);
+
+    try std.testing.expect(score == 9);
+
+    opp = RPSStates.Scissors;
+    me = RPSStates.Rock;
+
+    score = me.score_round(opp);
+
+    try std.testing.expect(score == 7);
+}