Find the largest product in a 2D array of any three consecutive numbers that are

Question

Find the largest product in a 2D array of any three consecutive numbers that are connected diagonally.

For example, X[4,3] = 71 can have the possible products 71*95*49, 71*4*79, 71*49*22 or 71*38*81. You must search the entire array to find the largest such product. The shape must be within the 2D array to perfom the calculation. If an index does not existto calculate a product (i.e., you are near an end) then the product does not need to be evaluated.

Use the following prototype that check if a product (current) is larger than the biggest.

void check_max(double current, double *biggest);

If current > biggest then the value of current is assigned to value at the address of the pointer.

Note: You have been provided with the following code

#include <stdio.h>

#include <string.h>

#define grid 20

int main(void) {

///////////////////////////////////////////////////////////////////////////////////////////

// DO NOT EDIT ANYTHING BETWEEN THE LONG COMMENT BARS.

// This 2D array is 20x20

double mat[grid][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}};

for (int n = 0; n < grid; n++) {

for (int m = 0; m < grid; m++)

mat[n][m] = mat[n][m]/10;

}

///////////////////////////////////////////////////////////////////////////////////////////

/*

   * Your code goes here

   *

   */

printf("The maximum product is %lf. ", max);

return 0;

}

Explanation / Answer

As I understand is from the given problem statement to find the longest product
of the given 2D array of 20 by 20..but i have present the method below.
It may help you to solve the given 2D grid

public void Solve() {
    string filename = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\input.txt";
    const int numbersInProduct = 4;

    decimal product = 0;

    int[,] inputSquare = readInput(filename);
    for (int col = 0; col < inputSquare.GetLength(0); col++) {
        for (int row = 0; row < inputSquare.GetLength(1); row++) {
            decimal tempProd;

            // Check Vertically
            if (row < inputSquare.GetLength(0) - numbersInProduct) {
                tempProd = inputSquare[col, row];
                for (int i = 1; i < numbersInProduct; i++) {
                    tempProd *= inputSquare[col, row + i];
                }
                product = Math.Max(product, tempProd);
            }

            // Check Horisontally
            if (col < inputSquare.GetLength(1) - numbersInProduct) {
                tempProd = inputSquare[col, row];
                for (int i = 1; i < numbersInProduct; i++) {
                    tempProd *= inputSquare[col + i, row];
                }
                product = Math.Max(product, tempProd);
            }

            // Check diagonally upwards / forwards
            if ((col < inputSquare.GetLength(0) - numbersInProduct) && (row >= numbersInProduct)) {
                tempProd = inputSquare[col, row];
                for (int i = 1; i < numbersInProduct; i++) {
                    tempProd *= inputSquare[col + i, row - i];
                }
                product = Math.Max(product, tempProd);
            }

            // Check diagonally Downwards / forwards
            if ((row < inputSquare.GetLength(0) - numbersInProduct) && (col < inputSquare.GetLength(1) - numbersInProduct)) {
                tempProd = inputSquare[col, row];
                for (int i = 1; i < numbersInProduct; i++) {
                    tempProd *= inputSquare[col + i, row + i];
                }
                product = Math.Max(product, tempProd);
            }
        }
    }
}

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