2024 Day 13 Part 2

2024/src/day13.zig

@@ -21,6 +21,7 @@ pub fn main() !void {
     const stdout = bw.writer();
 
     try stdout.print("{d}\n", .{try part1(games.items)});
+    try stdout.print("{d}\n", .{try part2(games.items)});
     try bw.flush();
 }
 
@@ -34,6 +35,17 @@ fn part1(games: []const Game) !i64 {
     return total;
 }
 
+fn part2(games: []const Game) !i64 {
+    var total: i64 = 0;
+    for (games) |game| {
+        const modded = game.mod(10000000000000);
+        const buttons = modded.solve() orelse continue;
+        const cost = 3 * buttons.a + 1 * buttons.b;
+        total += cost;
+    }
+    return total;
+}
+
 const Pos = struct {
     x: i64,
     y: i64,
@@ -161,6 +173,14 @@ const Game = struct {
             .b = @intCast(nB),
         };
     }
+
+    fn mod(self: Game, delta: i64) Game {
+        return Game{
+            .a = self.a,
+            .b = self.b,
+            .prize = self.prize.add(Move.new(delta, delta)),
+        };
+    }
 };
 
 fn takeLiteral(input: []const u8, want: []const u8) ?[]const u8 {