88 lines
1.6 KiB
Go
88 lines
1.6 KiB
Go
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package main
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import (
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"fmt"
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"math"
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"sort"
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"strings"
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"../../"
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)
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func main() {
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part1 := aoc.ArgIsSet("-1")
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justSort := aoc.ArgIsSet("-sort")
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input := aoc.StdinToStringSlice()
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var blacklists []Blacklist
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for i := range input {
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pts := strings.Split(input[i], "-")
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st := aoc.Atoi(pts[0])
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end := aoc.Atoi(pts[1])
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blacklists = append(blacklists, *CreateBlacklist(st, end))
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}
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sort.Sort(ByStart(blacklists))
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// Just output the sorted blacklists
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if justSort {
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for i := range blacklists {
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fmt.Print(blacklists[i].start, "-", blacklists[i].end, "\n")
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}
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return
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}
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// Find the lowest non-blacklisted IP
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if part1 {
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fmt.Println(findLowest(blacklists))
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return
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}
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// Count how many IPs are allowed
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var numIps, blIdx, ip int
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highestIp := int(math.Pow(2, 32))
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for ip <= highestIp {
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if blIdx >= len(blacklists) {
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break
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}
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if ip >= blacklists[blIdx].start {
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if ip <= blacklists[blIdx].end {
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ip = blacklists[blIdx].end + 1
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continue
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}
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blIdx++
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} else {
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numIps++
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ip++
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}
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}
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fmt.Println(numIps)
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}
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func findLowest(blacklists []Blacklist) int {
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var lowestIp int
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for i := range blacklists {
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if blacklists[i].hasIp(lowestIp) {
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lowestIp = blacklists[i].end + 1
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}
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}
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return lowestIp
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}
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type Blacklist struct {
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start, end int
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}
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func CreateBlacklist(st, end int) *Blacklist {
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return &Blacklist{st, end}
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}
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func (b *Blacklist) hasIp(inp int) bool {
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return inp >= b.start && inp <= b.end
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}
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type ByStart []Blacklist
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func (b ByStart) Len() int { return len(b) }
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func (b ByStart) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
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func (b ByStart) Less(i, j int) bool { return b[i].start < b[j].start }
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