AdventOfCode/2022/day6.scala

import java.nio.file.Files
import java.nio.file.Paths
import scala.util.control.NonLocalReturns.*

// 1M iterations: scala day6.jar  52.22s user 0.54s system 100% cpu 52.389 total
extension (s: String) def noDuplicates: Boolean =
	var i = 0
	while i < (s.length-1) do
		val c = s(i)
		var j = i + 1
		while j < s.length do
			if s(j) == c then return false
			j += 1
		i += 1
	return true

def first_unique_run_for(line: String, num: Int, skip: Int = 0): Int = returning {
	for i <- num.max(skip) until line.length do
		if line.substring(i-num, i).noDuplicates then
			throwReturn(i)
	throwReturn(-1)
}

// 1M iterations: scala day6.jar  20.44s user 0.07s system 100% cpu 20.371 total
def no_duplicates_copyless(s: String, right: Int, length: Int): Boolean =
	var i = right - length + 1
	while i < right do
		val c = s(i)
		var j = i + 1
		while j <= right do
			if c == s(j) then return false
			j += 1
		i += 1
	return true

def first_unique_run_while(line: String, num: Int, skip: Int = 0): Int =
	var right = num.max(skip)
	while right < line.length do
		if no_duplicates_copyless(line, right, num) then
			return right
		right += 1
	return -1

@main def main() =
	val line = Files.readString(Paths.get("input/6")).strip
	// do_once(line)
	perf_test(line, 1000000)

def do_once(line: String) =
	val four = first_unique_run_for(line, 4)
	val fourteen = first_unique_run_for(line, 14, four)
	println(four)
	println(fourteen)

def perf_test(line: String, n: Int) =
	var four = -1
	var fourteen = -1
	for i <- 1 to n do
		four = first_unique_run_while(line, 4)
		fourteen = first_unique_run_while(line, 14, four)
	println(four)
	println(fourteen)