131 lines
2.3 KiB
Go
131 lines
2.3 KiB
Go
package main
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import (
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"cmp"
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"math"
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"slices"
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"strconv"
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"strings"
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"github.com/StevanFreeborn/advent-of-code-2025/internal/file"
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)
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const RangeSeparatorCharacter = "-"
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type rnge struct {
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start int64
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end int64
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}
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func NewRange(rngeStr string) rnge {
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parts := strings.Split(strings.TrimSpace(rngeStr), RangeSeparatorCharacter)
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start, _ := strconv.ParseInt(parts[0], 10, 64)
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end, _ := strconv.ParseInt(parts[1], 10, 64)
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return rnge{
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start: start,
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end: end,
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}
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}
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func SolvePartOne(filePath string) int {
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input := file.ReadAllLines(filePath)
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parseIds := false
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ids := []int64{}
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ranges := []rnge{}
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for _, line := range input {
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if line == "" {
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parseIds = true
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}
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if parseIds {
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id, _ := strconv.ParseInt(line, 10, 64)
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ids = append(ids, id)
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continue
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}
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rnge := NewRange(line)
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ranges = append(ranges, rnge)
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}
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slices.SortFunc(ranges, func(a rnge, b rnge) int {
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return cmp.Compare(a.start, b.start)
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})
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mergedRanges := []rnge{
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ranges[0],
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}
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for _, currentRange := range ranges {
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lastMergedRange := mergedRanges[len(mergedRanges)-1]
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if currentRange.start > lastMergedRange.end {
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mergedRanges = append(mergedRanges, currentRange)
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continue
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}
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lastMergedRange.end = int64(math.Max(float64(lastMergedRange.end), float64(currentRange.end)))
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mergedRanges[len(mergedRanges)-1] = lastMergedRange
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}
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total := 0
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for _, id := range ids {
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for _, rnge := range mergedRanges {
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if id >= rnge.start && id <= rnge.end {
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total++
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break
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}
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}
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}
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return total
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}
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func SolvePartTwo(filePath string) int64 {
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input := file.ReadAllLines(filePath)
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ranges := []rnge{}
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for _, line := range input {
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if line == "" {
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break
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}
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rnge := NewRange(line)
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ranges = append(ranges, rnge)
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}
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slices.SortFunc(ranges, func(a rnge, b rnge) int {
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return cmp.Compare(a.start, b.start)
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})
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mergedRanges := []rnge{
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ranges[0],
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}
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for _, currentRange := range ranges {
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lastMergedRange := mergedRanges[len(mergedRanges)-1]
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if currentRange.start > lastMergedRange.end {
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mergedRanges = append(mergedRanges, currentRange)
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continue
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}
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lastMergedRange.end = int64(math.Max(float64(lastMergedRange.end), float64(currentRange.end)))
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mergedRanges[len(mergedRanges)-1] = lastMergedRange
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}
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total := int64(0)
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for _, rnge := range mergedRanges {
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diff := (rnge.end - rnge.start) + 1
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total += diff
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}
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return total
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}
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