1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97

void find_greatest_product()
{
int grid[20][20] = {{8, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 8}, //20x20 given grid/array
{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, 8, 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, 9, 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, 9, 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, 8, 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, 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, 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}};
int downRight_diag = 1; // all variables set
int upRight_diag = 1;
int left = 1;
int right = 1;
int up = 1;
int down = 1;
int firstMax = 0;
int absoluteMax = 0;
for(int i = 0; i < 20; i++)
{
for(int j = 0; j < 20; j++)
{
for(int k = i; k < 17; k++)
{
downRight_diag = grid[i][j]*grid[i+1][j+1]*grid[i+2][j+2]*grid[i+3][j+3];
down = grid[i][j]*grid[i+1][j]*grid[i+2][j]*grid[i+3][j];
if(downRight_diag > down && downRight_diag > firstMax)
firstMax = downRight_diag;
else if(down > downRight_diag && down > firstMax)
firstMax = down;
}
for(int l = i; l >= 3 && l < 20; l++)
{
upRight_diag = grid[i][j]*grid[i1][j+1]*grid[i2][j+2]*grid[i3][j+3];
up = grid[i][j]*grid[i1][j]*grid[i2][j]*grid[i3][j];
if(upRight_diag > firstMax)
firstMax = upRight_diag;
else if(up > firstMax)
firstMax = up;
}
if(j < 17)
{
left = grid[i][j]*grid[i][j+1]*grid[i][j+2]*grid[i][j+3];
if(left > firstMax)
firstMax = left;
}
if(j >= 3)
{
right = grid[i][j]*grid[i][j1]*grid[i][j2]*grid[i][j3];
if(right > firstMax)
firstMax = right;
}
if(firstMax > absoluteMax)
{
absoluteMax = firstMax;
}
downRight_diag = 1;
upRight_diag = 1;
left = 1;
right = 1;
up = 1;
down = 1;
firstMax = 0;
}
}
cout << absoluteMax << endl;
}
int main()
{
find_greatest_product(); // finding greatest product call funciton
return 0;
}
 