/**
 * P11-Largest product in a grid
 * In the 20×20 grid below, four numbers along a diagonal line have been marked in red.
 * The product of these numbers is 26 × 63 × 78 × 14 = 1788696.
 * What is the greatest product of four adjacent numbers in the same direction
 * (up, down, left, right, or diagonally) in the 20×20 grid?
 */
fun p11() {
    val grid = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08" +
            "49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00" +
            "81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65" +
            "52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91" +
            "22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80" +
            "24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50" +
            "32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70" +
            "67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21" +
            "24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72" +
            "21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95" +
            "78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92" +
            "16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57" +
            "86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58" +
            "19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40" +
            "04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66" +
            "88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69" +
            "04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36" +
            "20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16" +
            "20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54" +
            "01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48"

    var greatest = 0
    val rows: List<List<Int>> = grid.chunked(59).map { x -> x.split(" ").map { it.toInt() } }

    // vertical adjacent
    for (row in rows)
        for (i in 0..16)
            greatest = maxOf(greatest, row[i] * row[i + 1] * row[i + 2] * row[i + 3])

    // horizontal adjacent
    for (j in 0..16)
        for (i in 0 until 20)
            greatest = maxOf(greatest, rows[j][i] * rows[j + 1][i] * rows[j + 2][i] * rows[j + 3][i])
    // diagonal top left to bottom right adjacent
    for (j in 0..16)
        for (i in 0..16)
            greatest = maxOf(greatest, rows[j][i] * rows[j + 1][i + 1] * rows[j + 2][i + 2] * rows[j + 3][i + 3])

    // diagonal top right to bottom left adjacent
    for (j in 19 downTo 3)
        for (i in 0..16)
            greatest = maxOf(greatest, rows[j][i] * rows[j - 1][i + 1] * rows[j - 2][i + 2] * rows[j - 3][i + 3])

    println("A11: $greatest")
}