Day 13.

data.go

@@ -39,3 +39,6 @@ var Day11Data string
 
 //go:embed day_12/data.txt
 var Day12Data string
+
+//go:embed day_13/data.txt
+var Day13Data string

day_13/example_data.txt

@@ -0,0 +1,15 @@
+Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279

day_13/solution.go

@@ -0,0 +1,80 @@
+package day_13
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Arcade struct {
+	AX, AY         int
+	BX, BY         int
+	PrizeX, PrizeY int
+}
+
+// task:https://adventofcode.com/2024/day/13
+func SolveBasic(input string) int {
+	arcades := loadArcades(input)
+
+	sum := 0
+	for _, arcade := range arcades {
+		if price, solvable := solve(arcade); solvable {
+			sum += price
+		}
+	}
+
+	return sum
+}
+
+// task:https://adventofcode.com/2024/day/12#part2
+func SolveComplex(input string) int {
+	arcades := fixPrizes(loadArcades(input))
+
+	sum := 0
+	for _, arcade := range arcades {
+		if price, solvable := solve(arcade); solvable {
+			sum += price
+		}
+	}
+
+	return sum
+}
+
+func fixPrizes(arcades []Arcade) []Arcade {
+	for i := range arcades {
+		arcades[i].PrizeX += 10000000000000
+		arcades[i].PrizeY += 10000000000000
+	}
+	return arcades
+}
+
+func solve(arcade Arcade) (int, bool) {
+	a1 := arcade.AX
+	b1 := arcade.BX
+	a2 := arcade.AY
+	b2 := arcade.BY
+	c1 := arcade.PrizeX
+	c2 := arcade.PrizeY
+
+	A := (c1*b2 - b1*c2) / (a1*b2 - b1*a2)
+	B := (c2 - a2*A) / b2
+
+	if A*arcade.AX+B*arcade.BX == arcade.PrizeX &&
+		A*arcade.AY+B*arcade.BY == arcade.PrizeY {
+		return A*3 + B, true
+	}
+	return 0, false
+}
+
+func loadArcades(input string) []Arcade {
+	var arcades []Arcade
+
+	for _, arcadeLine := range strings.Split(input, "\n\n") {
+		lines := strings.Split(arcadeLine, "\n")
+		arcade := Arcade{}
+		fmt.Sscanf(lines[0], "Button A: X+%d, Y+%d", &arcade.AX, &arcade.AY)
+		fmt.Sscanf(lines[1], "Button B: X+%d, Y+%d", &arcade.BX, &arcade.BY)
+		fmt.Sscanf(lines[2], "Prize: X=%d, Y=%d", &arcade.PrizeX, &arcade.PrizeY)
+		arcades = append(arcades, arcade)
+	}
+	return arcades
+}

day_13/solution_test.go

@@ -0,0 +1,15 @@
+package day_13_test
+
+import (
+	"advent_of_code_2024/day_13"
+	"advent_of_code_2024/helpers"
+	_ "embed"
+	"testing"
+)
+
+//go:embed example_data.txt
+var ExampleData string
+
+func TestBasicSolutionExample(t *testing.T) {
+	helpers.Check(t, day_13.SolveBasic, helpers.Format(ExampleData), 480)
+}

solutions.go

@@ -13,6 +13,7 @@ import (
 	"advent_of_code_2024/day_10"
 	"advent_of_code_2024/day_11"
 	"advent_of_code_2024/day_12"
+	"advent_of_code_2024/day_13"
 )
 
 var solutions = map[string]Solution{
@@ -41,4 +42,6 @@ var solutions = map[string]Solution{
 	"12-basic":        {day_12.SolveBasic, Day12Data},
 	"12-complex":      {day_12.SolveComplex, Day12Data},
 	"12-complex-fast": {day_12.SolveComplexFast, Day12Data},
+	"13-basic":        {day_13.SolveBasic, Day13Data},
+	"13-complex":      {day_13.SolveComplex, Day13Data},
 }