Project Euler:Problem 11 Largest product in a grid

In the 20×20 grid below, four numbers along a diagonal line have been marked in red.
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

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?

#include <iostream>
using namespace std;

int main()
{
	int s[20][20];
	for (int i = 0; i < 20; i++)
	{
		for (int j = 0; j < 20; j++)
			cin >> s[i][j];
	}
	int max = 1;
	for (int i = 0; i < 20; i++)
	{
		for (int j = 0; j < 16; j++)
		{
			max = s[i][j] * s[i][j + 1] * s[i][j + 2] * s[i][j + 3]>max ? s[i][j] * s[i][j + 1] * s[i][j + 2] * s[i][j + 3] : max;
		}
	}
	for (int i = 0; i < 16; i++)
	{
		for (int j = 0; j < 20; j++)
		{
			max = s[i][j] * s[i + 1][j] * s[i + 2][j] * s[i + 3][j]>max ? s[i][j] * s[i + 1][j] * s[i + 2][j] * s[i + 3][j] : max;
		}
	}
	for (int i = 0; i < 16; i++)
	{
		for (int j = 0; j < 16; j++)
		{
			max = s[i][j] * s[i + 1][j + 1] * s[i + 2][j + 2] * s[i + 3][j + 3]>max ? s[i][j] * s[i + 1][j + 1] * s[i + 2][j + 2] * s[i + 3][j + 3] : max;
		}
	}
	for (int i = 0; i < 16; i++)
	{
		for (int j = 4; j < 20; j++)
		{
			max = s[i][j] * s[i + 1][j - 1] * s[i + 2][j - 2] * s[i + 3][j - 3]>max ? s[i][j] * s[i + 1][j - 1] * s[i + 2][j - 2] * s[i + 3][j - 3] : max;
		}
	}
	cout << max << endl;
	system("pause");
	return 0;
}