102 lines
3.0 KiB
Zig
102 lines
3.0 KiB
Zig
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const std = @import("std");
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pub const input = @embedFile("input/day02.txt");
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const test_input = @embedFile("input/day02_test1.txt");
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var gpa = std.heap.GeneralPurposeAllocator(.{ .safety = true }){};
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const allocator = gpa.allocator();
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const Choice = enum(usize) {
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Rock = 1,
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Paper = 2,
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Scissors = 3,
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fn from_opponent_char(char: u8) Choice {
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return switch (char) {
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'A' => Choice.Rock,
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'B' => Choice.Paper,
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'C' => Choice.Scissors,
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else => @panic("invalid opponent char!"),
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};
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}
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fn from_me_char(char: u8) Choice {
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return switch (char) {
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'X' => Choice.Rock,
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'Y' => Choice.Paper,
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'Z' => Choice.Scissors,
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else => @panic("invalid me char!"),
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};
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}
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fn from_outcome(self: Choice, outcome_char: u8) Choice {
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return switch (outcome_char) {
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'X' => self.lose_choice(),
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'Y' => self,
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'Z' => self.win_choice(),
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else => @panic("invalid outcome char!"),
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};
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}
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fn lose_choice(self: Choice) Choice {
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return switch (self) {
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Choice.Rock => Choice.Scissors,
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Choice.Paper => Choice.Rock,
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Choice.Scissors => Choice.Paper,
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};
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}
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fn win_choice(self: Choice) Choice {
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return switch (self) {
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Choice.Rock => Choice.Paper,
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Choice.Paper => Choice.Scissors,
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Choice.Scissors => Choice.Rock,
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};
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}
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fn beats(self: Choice, other: Choice) bool {
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return if (other.win_choice() == self) true else false;
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}
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fn ties(self: Choice, other: Choice) bool {
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return self == other;
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}
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};
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pub fn solve_part1(data: []const u8) usize {
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var lines = std.mem.split(u8, data, "\n");
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var score: usize = 0;
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while (lines.next()) |line| {
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if (std.mem.eql(u8, line, "")) break;
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var player_choices = std.mem.split(u8, line, " ");
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var opponent = Choice.from_opponent_char(player_choices.next().?[0]);
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var me = Choice.from_me_char(player_choices.next().?[0]);
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score += @enumToInt(me);
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if (me.beats(opponent)) {
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score += 6;
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} else if (me.ties(opponent)) {
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score += 3;
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}
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}
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return score;
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}
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pub fn solve_part2(data: []const u8) usize {
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var lines = std.mem.split(u8, data, "\n");
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var score: usize = 0;
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while (lines.next()) |line| {
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if (std.mem.eql(u8, line, "")) break;
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var player_choices = std.mem.split(u8, line, " ");
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var opponent = Choice.from_opponent_char(player_choices.next().?[0]);
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var me = opponent.from_outcome(player_choices.next().?[0]);
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score += @enumToInt(me);
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if (me.beats(opponent)) {
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score += 6;
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} else if (me.ties(opponent)) {
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score += 3;
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}
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}
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return score;
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}
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test "solves part1" {
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try std.testing.expectEqual(solve_part1(test_input), 15);
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}
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test "solves part2" {
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try std.testing.expectEqual(solve_part2(test_input), 12);
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}
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