2025 Day 5 Complete!

2025/day05/main.go

@@ -0,0 +1,111 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(inp []string) {
+	var ret int
+	fresh, ing := parseDB(inp)
+	for i := range ing {
+		for j := range fresh {
+			if fresh[j].Contains(ing[i]) {
+				ret++
+				break
+			}
+		}
+	}
+	fmt.Println("# Part 1")
+	fmt.Println(ret)
+}
+
+func part2(inp []string) {
+	fresh, _ := parseDB(inp)
+	for {
+		var toDel []*Range
+		for i := 0; i < len(fresh)-1; i++ {
+			for j := i + 1; j < len(fresh); j++ {
+				if fresh[i].Overlaps(fresh[j]) {
+					fresh[i].Merge(fresh[j])
+					toDel = append(toDel, fresh[j])
+				}
+			}
+			if len(toDel) > 0 {
+				break
+			}
+		}
+		if len(toDel) == 0 {
+			break
+		}
+		for i := range toDel {
+			for j := 0; j < len(fresh); j++ {
+				if fresh[j] == toDel[i] {
+					fresh = append(fresh[:j], fresh[j+1:]...)
+					break
+				}
+			}
+		}
+	}
+
+	// At this point, all ranges in 'fresh' should be non-overlapping
+	var ret int
+	for i := range fresh {
+		ret += fresh[i].Size()
+	}
+	fmt.Println("# Part 2")
+	fmt.Println(ret)
+}
+
+type Range struct {
+	beg, end int
+}
+
+func NewRange(inp string) *Range {
+	r := Range{}
+	fmt.Sscanf(inp, "%d-%d", &r.beg, &r.end)
+	return &r
+}
+func (r *Range) Contains(i int) bool { return r.beg <= i && i <= r.end }
+func (r *Range) Overlaps(r2 *Range) bool {
+	return r.Contains(r2.beg) || r.Contains(r2.end) || r2.Contains(r.beg) || r2.Contains(r.end)
+}
+func (r *Range) Merge(r2 *Range) {
+	if !r.Overlaps(r2) {
+		fmt.Println("Panic! Tried to merge non-overlapping ranges")
+		os.Exit(1)
+	}
+	r.beg = h.Min(r.beg, r2.beg)
+	r.end = h.Max(r.end, r2.end)
+}
+func (r *Range) Size() int     { return (r.end - r.beg) + 1 }
+func (r Range) String() string { return fmt.Sprintf("%d to %d", r.beg, r.end) }
+
+func parseDB(inp []string) ([]*Range, []int) {
+	var retRng []*Range
+	var retInt []int
+	inRanges := true
+	for i := range inp {
+		if inp[i] == "" {
+			inRanges = false
+			continue
+		}
+		if inRanges {
+			retRng = append(retRng, NewRange(inp[i]))
+			continue
+		}
+		var ri int
+		fmt.Sscanf(inp[i], "%d", &ri)
+		retInt = append(retInt, ri)
+	}
+	return retRng, retInt
+}