/*
--- Part Two ---

Considering every single measurement isn't as useful as you expected: there's just too much noise in
the data.

Instead, consider sums of a three-measurement sliding window. Again considering the above example:

```
199  A
200  A B
208  A B C
210    B C D
200  E   C D
207  E F   D
240  E F G
269    F G H
260      G H
263        H
```

Start by comparing the first and second three-measurement windows. The measurements in the first
window are marked A (199, 200, 208); their sum is 199 + 200 + 208 = 607. The second window is marked
B (200, 208, 210); its sum is 618. The sum of measurements in the second window is larger than the
sum of the first, so this first comparison increased.

Your goal now is to count the number of times the sum of measurements in this sliding window
increases from the previous sum. So, compare A with B, then compare B with C, then C with D, and so
on. Stop when there aren't enough measurements left to create a new three-measurement sum.

In the above example, the sum of each three-measurement window is as follows:

```
A: 607 (N/A - no previous sum)
B: 618 (increased)
C: 618 (no change)
D: 617 (decreased)
E: 647 (increased)
F: 716 (increased)
G: 769 (increased)
H: 792 (increased)
```

In this example, there are 5 sums that are larger than the previous sum.

Consider sums of a three-measurement sliding window. How many sums are larger than the previous sum?
*/

package com.curtislb.adventofcode.year2021.day01.part2

import com.curtislb.adventofcode.common.parse.parseInts
import java.nio.file.Path
import java.nio.file.Paths

/**
 * Returns the solution to the puzzle for 2021, day 1, part 2.
 *
 * @param inputPath The path to the input file for this puzzle.
 * @param windowSize The size of the measurement window to use when comparing sums.
 */
fun solve(inputPath: Path = Paths.get("..", "input", "input.txt"), windowSize: Int = 3): Int =
    inputPath.toFile()
        .readText()
        .parseInts()
        .windowed(windowSize + 1)
        .count { it.first() < it.last() }

fun main() {
    println(solve())
}
