package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func IntAbs(a int) int {
	if a >= 0 {
		return a
	}
	return -a
}

func main() {
	lists := readData("data.txt")
	fmt.Println(doTheThing(lists, 0))
	fmt.Println(doTheThing(lists, 1))
}

func readData(fileName string) (list [][]int) {
	fp, err := os.Open(fileName)
	if err != nil {
		panic(err)
	}

	scanner := bufio.NewScanner(fp)

	list = make([][]int, 0)

	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		sublist := make([]int, 0)

		for _, n := range strings.Split(line, " ") {
			value, err := strconv.Atoi(n)
			if err != nil {
				panic(err)
			}

			sublist = append(sublist, value)
		}

		list = append(list, sublist)
	}

	return
}

func doTheThing(list [][]int, canSkip int) (valid int) {
	for _, l := range list {
		if isValid(l, canSkip, -1) {
			valid += 1
		}
	}

	return
}

func isValid(l []int, canSkip int, toSkip int) bool {
	sumDiff := 0
	sumAbsDiff := 0

	for i := 0; i < len(l)-1; i++ {
		if i == toSkip {
			continue
		}

		j := i + 1
		if j == toSkip {
			j += 1
			if j >= len(l) {
				continue
			}
		}

		diff := l[i] - l[j]

		if diff == 0 || IntAbs(diff) > 3 || IntAbs(sumDiff+diff) != sumAbsDiff+IntAbs(diff) {
			if canSkip > 0 {
				return isValid(l, canSkip-1, i-1) || isValid(l, canSkip-1, i) || isValid(l, canSkip-1, j)
			} else {
				return false
			}
		}

		sumDiff += diff
		sumAbsDiff += IntAbs(diff)
	}

	return true
}