feat(2025): add day5

2025/day5/day5.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+type Range struct {
+	Start, End int
+}
+
+func readInput() ([]Range, []int) {
+	data, _ := os.ReadFile("input.txt")
+	content := strings.TrimSpace(string(data))
+	lines := strings.Split(content, "\n")
+	ranges := []Range{}
+	for len(lines) > 0 {
+		line := lines[0]
+		lines = lines[1:]
+		parts := strings.Split(line, "-")
+		if len(parts) < 2 {
+			break
+		}
+
+		start, _ := strconv.Atoi(strings.TrimSpace(parts[0]))
+		end, _ := strconv.Atoi(strings.TrimSpace(parts[1]))
+		ranges = append(ranges, Range{start, end})
+	}
+
+	candidates := []int{}
+	for len(lines) > 0 {
+		line := lines[0]
+		lines = lines[1:]
+		candidate, _ := strconv.Atoi(strings.TrimSpace(line))
+		candidates = append(candidates, candidate)
+
+	}
+
+	return ranges, candidates
+}
+
+func part1() {
+	ranges, candidates := readInput()
+	count := 0
+	for _, candidate := range candidates {
+		for _, r := range ranges {
+			if candidate >= r.Start && candidate <= r.End {
+				count++
+				break
+			}
+		}
+	}
+
+	fmt.Printf("%d\n", count)
+}
+
+func part2() {
+	ranges, _ := readInput()
+	sort.Slice(ranges, func(i, j int) bool {
+		return ranges[i].Start < ranges[j].Start
+	})
+
+	merged := []Range{ranges[0]}
+	for _, cur := range ranges[1:] {
+		last := &merged[len(merged)-1]
+
+		if cur.Start <= last.End {
+			if cur.End > last.End {
+				last.End = cur.End
+			}
+		} else {
+			merged = append(merged, cur)
+		}
+	}
+
+	count := 0
+	for _, m := range merged {
+		count += (m.End - m.Start + 1)
+	}
+	fmt.Printf("%d\n", count)
+}
+
+func main() {
+	part1()
+	part2()
+}

2025/day5/go.mod

@@ -0,0 +1,3 @@
+module day5
+
+go 1.23.4