package de.huddeldaddel.euler

import java.util.Arrays

/**
 * Solution for https://projecteuler.net/problem=11
 */
fun main() {
    val problem11 = Problem11()
    val grid = Problem11.Grid()
    val values = longArrayOf(
            problem11.getMaxAdjacentNumberProductVertical(grid),
            problem11.getMaxAdjacentNumberProductHorizontal(grid),
            problem11.getMaxAdjacentNumberProductDiagonal1(grid),
            problem11.getMaxAdjacentNumberProductDiagonal2(grid))
    Arrays.sort(values)
    println(values[3])
}

class Problem11 {

    fun getMaxAdjacentNumberProductVertical(grid: Grid): Long {
        var result: Long = 0
        for (column in 0..19) {
            for (row in 0 until 20 - SEQUENCE_SIZE) {
                var product: Long = 1
                for (i in 0 until SEQUENCE_SIZE)
                    product *= grid[row + i, column].toLong()
                result = Math.max(result, product)
            }
        }
        return result
    }

    fun getMaxAdjacentNumberProductHorizontal(grid: Grid): Long {
        var result: Long = 0
        for (row in 0..19) {
            for (column in 0 until 20 - SEQUENCE_SIZE) {
                var product: Long = 1
                for (i in 0 until SEQUENCE_SIZE)
                    product *= grid[row, column + i].toLong()
                result = Math.max(result, product)
            }
        }
        return result
    }

    fun getMaxAdjacentNumberProductDiagonal1(grid: Grid): Long {
        var result: Long = 0
        for (row in 0 until 20 - SEQUENCE_SIZE) {
            for (column in 0 until 20 - SEQUENCE_SIZE) {
                var product: Long = 1
                for (i in 0 until SEQUENCE_SIZE)
                    product *= grid[row + i, column + i].toLong()
                result = Math.max(result, product)
            }
        }
        return result
    }

    fun getMaxAdjacentNumberProductDiagonal2(grid: Grid): Long {
        var result: Long = 0
        for (row in SEQUENCE_SIZE..19) {
            for (column in 0 until 20 - SEQUENCE_SIZE) {
                var product: Long = 1
                for (i in 0 until SEQUENCE_SIZE)
                    product *= grid[row - i, column + i].toLong()
                result = Math.max(result, product)
            }
        }
        return result
    }

    class Grid {

        private val values = Array(20) { IntArray(20) }

        init {
            val text =
                    "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08\n" +
                    "49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00\n" +
                    "81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65\n" +
                    "52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91\n" +
                    "22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80\n" +
                    "24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50\n" +
                    "32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70\n" +
                    "67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21\n" +
                    "24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72\n" +
                    "21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95\n" +
                    "78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92\n" +
                    "16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57\n" +
                    "86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58\n" +
                    "19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40\n" +
                    "04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66\n" +
                    "88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69\n" +
                    "04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36\n" +
                    "20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16\n" +
                    "20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54\n" +
                    "01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48"

            val lines = text.split("\n".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
            for (i in 0..19) {
                val numbers = lines[i].split(" ".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
                for (j in 0..19)
                    values[i][j] = Integer.parseInt(numbers[j])
            }
        }

        operator fun get(row: Int, column: Int): Int {
            return values[row][column]
        }

    }

    companion object {

        private val SEQUENCE_SIZE = 4

    }

}
