feat: add day 2 2024

aoc2024/day02/example.txt

@@ -0,0 +1,6 @@
+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9

aoc2024/day02/main.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"bufio"
+	_ "embed"
+	"fmt"
+	"strings"
+
+	aoc "go.sour.is/advent-of-code"
+)
+
+// var log = aoc.Log
+
+func main() { aoc.MustResult(aoc.Runner(run)) }
+
+type result struct {
+	valuePT1 int
+	valuePT2 int
+}
+
+func (r result) String() string { return fmt.Sprintf("%#v", r) }
+
+func run(scan *bufio.Scanner) (*result, error) {
+
+	sum := 0
+	sum2 := 0
+
+	for scan.Scan() {
+		txt := scan.Text()
+		row := aoc.ReadStringToInts(strings.Fields(txt))
+
+		good, bad := testSafety(row)
+		if good {
+			sum++
+			sum2++
+			continue
+		}
+
+		for i := max(0, bad-1); i < min(bad+2, len(row)); i++ {
+			arr := cut(i, row)
+
+			good, _ := testSafety(arr)
+			if good {
+				sum2++
+				break
+			}
+		}
+	}
+
+	return &result{valuePT1: sum, valuePT2: sum2}, nil
+}
+
+func testSafety(row []int) (bool, int) {
+	good := true
+	bad := -1
+	increasing := false
+	decreasing := false
+
+	for i, v := range row[1:] {
+		if v > row[i] {
+			increasing = true
+		}
+		if v < row[i] {
+			decreasing = true
+		}
+
+		if difference := aoc.ABS(v - row[i]); difference < 1 || difference > 3 {
+			good = false
+			bad = i
+			break
+		}
+
+		if increasing && decreasing {
+			good = false
+			bad = i
+			break
+		}
+	}
+
+	return good, bad
+}
+
+func cut(i int, values []int) []int {
+	arr := make([]int, 0, len(values))
+	arr = append(arr, values[:i]...)
+	arr = append(arr, values[i+1:]...)
+	return arr
+}

aoc2024/day02/main_test.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"testing"
+
+	_ "embed"
+
+	"github.com/matryer/is"
+)
+
+//go:embed example.txt
+var example []byte
+
+//go:embed input.txt
+var input []byte
+
+func TestExample(t *testing.T) {
+	is := is.New(t)
+	scan := bufio.NewScanner(bytes.NewReader(example))
+
+	result, err := run(scan)
+	is.NoErr(err)
+
+	t.Log(result)
+	is.Equal(result.valuePT1, 2)
+	is.Equal(result.valuePT2, 4)
+}
+
+func TestSolution(t *testing.T) {
+	is := is.New(t)
+	scan := bufio.NewScanner(bytes.NewReader(input))
+
+	result, err := run(scan)
+	is.NoErr(err)
+
+	t.Log(result)
+	is.Equal(result.valuePT1, 486)
+	is.True(result.valuePT2 > 517)
+	is.True(result.valuePT2 > 523)
+	is.Equal(result.valuePT2, 540)
+}