/* Solution to Day 4: Camp Cleanup
 * https://adventofcode.com/2022/day/4
 */
package day04

import java.io.File

fun main() {
    val fileName =
//        "day04_sample.txt"
        "day04_input.txt"
    val assignmentPairs = readInput(fileName)

    // Part 1: count assignment pairs where one fully contains the other
    val p1Count = assignmentPairs.count { (firstRange, secondRange) ->
        firstRange subset secondRange || secondRange subset firstRange
    }
    println("Part 1: $p1Count")

    // Part 2: count overlapping assignment pairs
    val p2Count = assignmentPairs.count { (firstRange, secondRange) ->
        firstRange overlaps secondRange
    }
    println("Part 2: $p2Count")
}

/**
 * Reads and parses input data according to the problem statement.
 */
fun readInput(fileName: String): List<AssignmentPair> {
    return File("inputs", fileName)
        .readLines()
        .asSequence()
        .map { AssignmentPair from it }
        .toList()
}

/**
 * Checks if this IntRange is a subset of the other [IntRange].
 */
infix fun IntRange.subset(other: IntRange): Boolean {
    return other.first <= this.first && this.last <= other.last
}

/**
 * Checks if this IntRange overlaps with the other [IntRange]
 * by at least one element.
 */
infix fun IntRange.overlaps(other: IntRange): Boolean {
    return this.first <= other.last && other.first <= this.last
}
