solution: year-2024/day-01

go.work

@@ -12,4 +12,5 @@ use (
 	./solutions/year-2022/day-05
 	./solutions/year-2022/day-06
 	./solutions/year-2023/day-01
+	./solutions/year-2024/day-01
 )

solutions/year-2024/day-01/go.mod

@@ -0,0 +1,3 @@
+module github.com/atifcppprogrammer/advent-of-golang/solutions/year-2024/day-01
+
+go 1.23.4

solutions/year-2024/day-01/main.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"github.com/atifcppprogrammer/advent-of-golang/internal/utilities"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	filepath := utilities.GetInputFile()
+	lines, _ := utilities.ReadLines(filepath)
+
+	result := solution(lines)
+	utilities.PrintSolution("2024", 01, "", strconv.Itoa(result))
+}
+
+func solution(lines []string) (result int) {
+	var (
+		count = len(lines)
+		l1    = make(sort.IntSlice, count)
+		l2    = make(sort.IntSlice, count)
+	)
+
+	for i, line := range lines {
+		val1, val2, _ := strings.Cut(line, "   ")
+		num1, _ := strconv.Atoi(val1)
+		num2, _ := strconv.Atoi(val2)
+		l1[i] = num1
+		l2[i] = num2
+	}
+
+	if utilities.SolutionPart == 1 {
+		sort.Sort(l1)
+		sort.Sort(l2)
+
+		for i := 0; i < count; i++ {
+			diff := l1[i] - l2[i]
+			if diff < 0 {
+				result += -diff
+			} else {
+				result += +diff
+			}
+		}
+
+		return
+	}
+
+	if utilities.SolutionPart == 2 {
+		numCounts := make(map[int]int)
+
+		for _, num := range l2 {
+			if _, exists := numCounts[num]; !exists {
+				numCounts[num] = 1
+			} else {
+				numCounts[num]++
+			}
+		}
+
+		for _, num := range l1 {
+			if count, exists := numCounts[num]; exists {
+				result += num * count
+			}
+		}
+	}
+
+	return
+}

solutions/year-2024/day-01/main_test.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/atifcppprogrammer/advent-of-golang/internal/utilities"
+)
+
+func setSolutionPartEnv(t *testing.T, solutionPart string) {
+	t.Setenv("PART", solutionPart)
+	utilities.SetSolutionPart()
+}
+
+func TestSolution(t *testing.T) {
+	t.Run("solves example input correctly", func(t *testing.T) {
+		lines := []string{
+			"3   4",
+			"4   3",
+			"2   5",
+			"1   3",
+			"3   9",
+			"3   3",
+		}
+
+		tests := []struct {
+			solutionPart string
+			want         int
+		}{
+			{solutionPart: "1", want: 11},
+			{solutionPart: "2", want: 31},
+		}
+		for _, tt := range tests {
+			t.Run(fmt.Sprintf("solves example correct for part %s", tt.solutionPart), func(t *testing.T) {
+				setSolutionPartEnv(t, tt.solutionPart)
+				got, want := solution(lines), tt.want
+				if got != want {
+					t.Errorf("want %d got %d", want, got)
+				}
+			})
+		}
+	})
+}