From 5229a41ca76f0f4ac15872a031d0ad782824c4ee Mon Sep 17 00:00:00 2001
From: Martin Ashby <martin@ashbysoft.com>
Date: Sat, 2 Dec 2023 15:09:27 +0000
Subject: day2

---
 day2.zig | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

(limited to 'day2.zig')

diff --git a/day2.zig b/day2.zig
index d4f8f85..9ce71d9 100644
--- a/day2.zig
+++ b/day2.zig
@@ -1,8 +1,73 @@
 const std = @import("std");
 const Setup = @import("common.zig").Setup;
 
+const Colour = enum { 
+    red, green, blue ,
+    fn parse(str: []const u8) !Colour {
+        const ei = @typeInfo(Colour).Enum;
+        inline for (ei.fields) |field| {
+            if (std.mem.eql(u8, field.name, str)) {
+                return @enumFromInt(field.value);
+            }
+        } else {
+            return error.InvalidColour;
+        }
+    }
+};
+
 pub fn main() !void {
     var setup = try Setup.get();
     defer setup.deinit();
-    
+    var sum: u32 = 0;
+    var lines = std.mem.splitScalar(u8, setup.input, '\n');
+    const maxred: u32 = 12;
+    const maxgreen: u32 = 13;
+    const maxblue: u32 = 14;
+    while (lines.next()) |line| {
+        var spl = std.mem.split(u8, line, ": ");
+        const game_no_str = spl.first();
+        const game_no = try std.fmt.parseInt(u32, game_no_str[5..game_no_str.len], 10); // "Game " prefix skipped
+        const game_str = spl.next() orelse return error.NoGame;
+        var turns = std.mem.split(u8, game_str, "; ");
+        var gamemaxred: u32 = 0;
+        var gamemaxgreen: u32 = 0;
+        var gamemaxblue: u32 = 0;
+
+        while (turns.next()) |turn| {
+            var cols = std.mem.split(u8, turn, ", ");
+            while (cols.next()) |col| {
+                var spl2 = std.mem.split(u8, col, " ");
+                const num = try std.fmt.parseInt(u32, spl2.first(), 10);
+                const col_str = spl2.next() orelse return error.NoColour;
+                const c = try Colour.parse(col_str);
+                switch(c) {
+                    .blue => {
+                        gamemaxblue = @max(num, gamemaxblue);
+                    },
+                    .green => {
+                        gamemaxgreen = @max(num, gamemaxgreen);
+                    },
+                    .red => {
+                        gamemaxred = @max(num, gamemaxred);
+                    },
+                }
+            }
+        }
+        switch (setup.part) {
+            .pt1 => {
+                if (gamemaxblue <= maxblue and gamemaxgreen <= maxgreen and gamemaxred <= maxred) {
+                    sum += game_no;
+                } else {
+                    //std.log.warn("game was impossible {s}", .{line});
+                }
+            },
+            .pt2 => {
+                const power = gamemaxblue * gamemaxgreen * gamemaxred;
+                sum += power;
+            },
+        }
+        
+        //turns.next()
+    }
+    try std.fmt.format(std.io.getStdOut().writer(), "answer: {}\n", .{sum});
 }
\ No newline at end of file
-- 
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