projecteuler/0011.cpp at master · foodini/projecteuler · GitHub

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#include <stdio.h>

int grid[20][20] =
{
	{ 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,}
};

int main()
{
	long long product;
	long long max = 0;

	for (int i=0; i<20; i++)
	{
		for (int j=0; j<=16; j++)
		{
			product = 1;
			for (int n=0; n<4; n++)
				product *= grid[i][j+n];
			if (product > max)
				max = product;
		}
	}

	for (int i=0; i<=16; i++)
	{
		for (int j=0; j<20; j++)
		{
			product = 1;
			for (int n=0; n<4; n++)
				product *= grid[i+n][j];
			if (product > max)
				max = product;
		}
	}

	for (int i=0; i<=16; i++)
	{
		for (int j=0; j<=16; j++)
		{
			product = 1;
			for (int n=0; n<4; n++)
				product *= grid[i+n][j+n];
			if (product > max)
				max = product;
		}
	}

	for (int i=0; i<=16; i++)
	{
		for (int j=3; j<20; j++)
		{
			product = 1;
			for (int n=0; n<4; n++)
				product *= grid[i+n][j-n];
			if (product > max)
				max = product;
		}
	}

	printf ("%lld\n", max);
}