52 lines
962 B
Go
52 lines
962 B
Go
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package main
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import (
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"fmt"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
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func main() {
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inp := h.StdinToString()
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fmt.Println("# Part 1")
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fmt.Printf("First Start of Packet @ %d\n", findFirstStartOfPacket(inp))
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fmt.Println("")
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fmt.Println("# Part 2")
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fmt.Printf("First Start of Message @ %d\n", findFirstStartOfMessage(inp))
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}
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func findFirstStartOfPacket(inp string) int {
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return findFirstWithXUnique(inp, 4)
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}
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func findFirstStartOfMessage(inp string) int {
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return findFirstWithXUnique(inp, 14)
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}
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func findFirstWithXUnique(inp string, x int) int {
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for i := range inp {
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if i < x {
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continue
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}
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if findUniqueCountBefore(inp, i) >= x {
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return i + 1
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}
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}
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return -1
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}
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func findUniqueCountBefore(inp string, pos int) int {
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if len(inp) < pos {
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return -1
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}
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counts := make(map[byte]int)
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for i := pos; i >= 0; i-- {
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if _, ok := counts[inp[i]]; !ok {
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counts[inp[i]]++
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} else {
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return len(counts)
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}
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}
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return pos
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}
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