Largest Product in a Grid

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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 a given arr grid?

Product Grid

Solution

/* Solution Function */
let largestGridProduct = (array, numberOfAdjacentValues) => {

    let largestProduct = 0

    /* Variables to iterate through nested array */
    let row
    let column

    /* How many indexes adjecent to each cell we need to multiply */
    let maxOffset = (numberOfAdjacentValues - 1) || 3

    /* Nested for loop goes through each cell in nested array */
    for(row = 0; row < array.length; row ++){
        for(column = 0; column < array[0].length; column ++){

            /* Value of current cell */
            let cell = array[row][column]
            /* Stores temporary product */
            let product

            /* Iterate though adjacent row and column indices */
            let i
            let j

            /* Adjacent horizontally */
            product = cell
            for(i = 1; i <= maxOffset; i ++ ){
                if(array[row] && array[row][column + i]){
                    product = product * array[row][column + i]
                }else{
                    break
                }
            }
            if(product > largestProduct){
                largestProduct = product
            }

            /* Adjacent vertically */
            product = cell
            for(i = 1; i <= maxOffset; i ++ ){
                if(array[row + i] && array[row + i][column]){
                    product = product * array[row + i][column]
                }else{
                    break
                }
            }
            if(product > largestProduct){
                largestProduct = product
            }
           
            /* Adjacent diagnonal topleft-bottomright */
            product = cell
            for(i = 1; i <= maxOffset; i ++ ){
                if(array[row + i] && array[row + i][column + i]){
                    product = product * array[row + i][column + i]
                }else{
                    break
                }
            }
            if(product > largestProduct){
                largestProduct = product
            }

            /* Adjacent diagnonal bottomleft-topright */
            product = cell
            for(i = 1; i <= maxOffset; i ++ ){
                if(array[row - i] && array[row - i][column + i]){
                    product = product * array[row - i][column + i]
                }else{
                    break
                }
            }
            if(product > largestProduct){
                largestProduct = product
            }
        }
    }

    return largestProduct

}

/* Check Solution */

let grid = [
    [8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8],
    [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0],
    [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65],
    [52, 70, 95, 23, 4, 60, 11, 42, 69, 24, 68, 56, 1, 32, 56, 71, 37, 2, 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, 3, 45, 2, 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, 2, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21],
    [24, 55, 58, 5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
    [21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35, 14, 0, 61, 33, 97, 34, 31, 33, 95],
    [78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80, 4, 62, 16, 14, 9, 53, 56, 92],
    [16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0, 17, 54, 24, 36, 29, 85, 57],
    [86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
    [19, 80, 81, 68, 5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 4, 89, 55, 40],
    [4, 52, 8, 83, 97, 35, 99, 16, 7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
    [88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
    [4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36],
    [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 4, 36, 16],
    [20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 5, 54],
    [1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89, 19, 67, 48]
  ]
  
  let testGrid = [
    [40, 17, 81, 18, 57],
    [74, 4, 36, 16, 29],
    [36, 42, 69, 73, 45],
    [51, 54, 69, 16, 92],
    [7, 97, 57, 32, 16]
  ]

console.log('Result is ' + largestGridProduct(grid))
Ganesh H