problem 11 矩阵中连续四个数的最大积

http://projecteuler.net/problem=11

暴力枚举

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
	int matrix[410] ={
		8,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,8,
			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 M[25][25];
	for(i=0;i<400; i++)
	{
		M[i/20][i%20] = matrix[i];
	}
	int dir[8][2] = {{1,0},{0,1},{-1,0},{0,-1},{-1,-1},{1,1},{-1,1},{1,-1}};
	int ans = 0;
	for(i = 0; i < 20;i++)
	{
		for(j = 0; j < 20; j++)
		{
			int k;
			for(k = 0; k < 8; k++)
			{
				int x,y;
				x = i;
				y = j;
				int n = 4;
				int product = 1;
				while(n--)
				{
				x += dir[k][0];
				y +=  dir[k][1];
				product *= M[x][y];

				}
				if(product > ans)
				{
					ans = product;
				}


			}
		}
	}
	printf("%d\n",ans);

	return 0;
}