advent-of-code-2021/1/part2.go

package main

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

func main() {
	count := 0
	windows := [4]int{0, 0, 0, 0}
	i := 1

	s := bufio.NewScanner(os.Stdin)
	for s.Scan() {
		currentWindow := i % 4
		nextWindow := (i + 1) % 4

		value, _ := strconv.Atoi(s.Text())
		for j := 0; j < 4; j++ {
			if j != currentWindow {
				windows[j] += value
			}
		}

		//fmt.Println(value, windows, currentWindow, nextWindow, windows[nextWindow], windows[currentWindow])
		// skip the first 3 values to populate the windows
		if i > 3 && windows[nextWindow] > windows[currentWindow] {
			count++
		}

		windows[currentWindow] = 0
		i++
	}

	fmt.Println(count)
}