day06

2023/go/day06/day06.go

@@ -0,0 +1,71 @@
+package day06
+
+import (
+	"fmt"
+	"math"
+)
+
+type Input struct {
+	Time uint64
+	Distance uint64
+}
+func Part1(input string) int {
+	answer := 1.0
+	ins := parseInput1(input)
+	for _, in := range ins {
+		t1, t2, _ := solveQuadratic(1, float64(in.Time) * -1, float64(in.Distance))
+		fmt.Printf("t1: %v t2: %v ans: %v\n", t1, t2, (t1 - t2 + 1))
+		answer *= (t1 - t2 + 1)
+
+	}
+	return int(answer)
+}
+
+func Part2(input string) int {
+	answer := 1.0
+	ins := parseInput2(input)
+	for _, in := range ins {
+		t1, t2, _ := solveQuadratic(1, float64(in.Time) * -1, float64(in.Distance))
+		fmt.Printf("t1: %v t2: %v ans: %v\n", t1, t2, (t1 - t2 + 1))
+		answer *= (t1 - t2 + 1)
+
+	}
+	return int(answer)}
+
+func parseInput1(input string) []Input {
+	var in []Input
+	in = append(in, Input{46, 214})
+	in = append(in, Input{80, 1177})
+	in = append(in, Input{78, 1402})
+	in = append(in, Input{66, 1024})
+	return in
+}
+
+func parseInput2(input string) []Input {
+	var in []Input
+	in = append(in, Input{46807866, 214117714021024})
+	return in
+}
+
+func solveQuadratic(a, b, c float64) (float64, float64, error) {
+	// Calculate the discriminant
+	discriminant := b*b - 4*a*c
+
+	// Check if the discriminant is non-negative
+	if discriminant < 0 {
+		return 0, 0, fmt.Errorf("no real roots, discriminant is negative")
+	}
+
+	// Calculate the roots
+	root1 := (-b + math.Sqrt(discriminant)) / (2 * a)
+	root2 := (-b - math.Sqrt(discriminant)) / (2 * a)
+
+	if isWholeNumber(root1) { root1 = root1 - 1.0 }
+	if isWholeNumber(root2) { root2 = root2 + 1.0 }
+	return math.Floor(root1), math.Ceil(root2), nil
+}
+
+func isWholeNumber(x float64) bool {
+	rounded := math.Round(x)
+	return x == rounded
+}

2023/go/day06/day06_test.go

@@ -0,0 +1,17 @@
+package day06
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1("")
+	require.Equal(t, 512295, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2("")
+	require.Equal(t, 36530883, r)
+}

2023/go/day06/input.txt

@@ -0,0 +1,2 @@
+Time:        46     80     78     66
+Distance:   214   1177   1402   1024