feat: completed day 5 for advent of code 2025

2025/cmd/root.go

@@ -13,6 +13,7 @@ import (
 	"cpatino.com/advent-of-code/2025/day02"
 	"cpatino.com/advent-of-code/2025/day03"
 	"cpatino.com/advent-of-code/2025/day04"
+	"cpatino.com/advent-of-code/2025/day05"
 )
 
 var days = map[int]func(string) (any, any){
@@ -20,6 +21,7 @@ var days = map[int]func(string) (any, any){
 	2: day02.Run,
 	3: day03.Run,
 	4: day04.Run,
+	5: day05.Run,
 }
 
 var rootCmd = &cobra.Command{

2025/day05/day05.go

@@ -0,0 +1,132 @@
+package day05
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func Part1(ranges [][2]int, ids []int) int {
+	freshCount := 0
+	for _, id := range ids {
+		for _, r := range ranges {
+			if id >= r[0] && id <= r[1] {
+				freshCount++
+				break
+			}
+		}
+	}
+	return freshCount
+}
+
+func Part2(ranges [][2]int) int {
+	if len(ranges) == 0 {
+		return 0
+	}
+
+	sorted := make([][2]int, len(ranges))
+	copy(sorted, ranges)
+	for i := 0; i < len(sorted)-1; i++ {
+		for j := i + 1; j < len(sorted); j++ {
+			if sorted[j][0] < sorted[i][0] {
+				sorted[i], sorted[j] = sorted[j], sorted[i]
+			}
+		}
+	}
+
+	merged := make([][2]int, 0)
+	current := sorted[0]
+	for i := 1; i < len(sorted); i++ {
+		next := sorted[i]
+		if next[0] <= current[1]+1 {
+			if next[1] > current[1] {
+				current[1] = next[1]
+			}
+		} else {
+			merged = append(merged, current)
+			current = next
+		}
+	}
+	merged = append(merged, current)
+
+	total := 0
+	for _, r := range merged {
+		total += r[1] - r[0] + 1
+	}
+	return total
+}
+
+func Run(filename string) (any, any) {
+	file, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	lines := make([]string, 0)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+
+	sep := 0
+	for i, line := range lines {
+		if line == "" {
+			sep = i
+			break
+		}
+	}
+
+	rangeLines := lines[:sep]
+	idLines := lines[sep+1:]
+
+	ranges := parseRanges(rangeLines)
+	ids := parseIDs(idLines)
+
+	part1 := Part1(ranges, ids)
+	part2 := Part2(ranges)
+
+	return part1, part2
+}
+
+func parseRanges(lines []string) [][2]int {
+	ranges := make([][2]int, 0)
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+
+		parts := strings.Split(line, "-")
+		if len(parts) != 2 {
+			continue
+		}
+
+		start, err1 := strconv.Atoi(parts[0])
+		end, err2 := strconv.Atoi(parts[1])
+		if err1 == nil && err2 == nil {
+			ranges = append(ranges, [2]int{start, end})
+		}
+	}
+
+	return ranges
+}
+
+func parseIDs(lines []string) []int {
+	ids := make([]int, 0)
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+
+		id, err := strconv.Atoi(line)
+		if err == nil {
+			ids = append(ids, id)
+		}
+	}
+
+	return ids
+}

2025/day05/day05_test.go

@@ -0,0 +1,34 @@
+package day05
+
+import (
+	"os"
+	"testing"
+)
+
+type TestCase struct {
+	FileName string
+	Part1    any
+	Part2    any
+}
+
+func TestDay05(t *testing.T) {
+	tests := []TestCase{
+		{"test.txt", 3, 14},
+		{"input.txt", 798, 366181852921027},
+	}
+
+	for _, test := range tests {
+		if _, err := os.Stat(test.FileName); os.IsNotExist(err) {
+			t.Fatalf("test file does not exist: %v", test.FileName)
+		}
+
+		part1, part2 := Run(test.FileName)
+		if test.Part1 != nil && part1 != test.Part1 {
+			t.Fatalf("%s: unexpected part1:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part1, part1)
+		}
+
+		if test.Part2 != nil && part2 != test.Part2 {
+			t.Fatalf("%s: unexpected part2:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part2, part2)
+		}
+	}
+}

2025/day05/test.txt

@@ -0,0 +1,11 @@
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32