(C언어)프로젝트 오일러(Project Euler)11. 20×20 격자에서 연속된 네 숫자의 곱 중 최대값

아래와 같은 20×20 격자가 있습니다.

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

위에서 대각선 방향으로 연속된 붉은 숫자 네 개의 곱은 26 × 63 × 78 × 14 = 1788696 입니다.

그러면 수평, 수직, 또는 대각선 방향으로 연속된 숫자 네 개의 곱 중 최대값은 얼마입니까?

 

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#include <stdio.h>
 
int main(void)
{
    int line[20][20= { {8,2,22,97,38,15,0,40,0,75,4,5,7,78,52,12,50,77,91,8},
                        {49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62},
                        {81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65},
                        {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},
                        {32,98,81,28,64,23,57,10,26,38,40,67,59,54,70,66,18,38,64,70},
                        {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},
                        {16,39,5,42,96,35,31,47,55,58,8,24,0,17,54,24,36,29,85,57},
                        {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 temp, i, j;
    int max1 = 0, max2 = 0, max3 = 0, max4 = 0;
 
    for (i = 0; i < 20; i++)                //수평 검사
    {
        for (j = 0; j < 17; j++)
        {
            temp = line[i][j] * line[i][j + 1* line[i][j + 2* line[i][j + 3];
            if (max1 < temp)
                max1 = temp;
        }
    }
 
    for (i = 0; i < 17; i++)                //수직 검사
    {
        for (j = 0; j < 20; j++)
        {
            temp = line[i][j] * line[i + 1][j] * line[i + 2][j] * line[i + 3][j];
            if (max2 < temp)
                max2 = temp;
        }
    }
 
    for (i = 0; i < 17; i++)                //우측 방향 대각선 검사
    {
        for (j = 0; j < 17; j++)
        {
            temp = line[i][j] * line[i + 1][j + 1* line[i + 2][j + 2* line[i + 3][j + 3];
            if (max3 < temp)
                max3 = temp;
        }
    }
    for (i = 3; i < 17; i++)                //좌측 방향 대각선 검사
    {
        for (j = 0; j < 17; j++)
        {
            temp = line[i][j] * line[i - 1][j + 1* line[i - 2][j + 2* line[i - 3][j + 3];
            if (max4 < temp)
                max4 = temp;
        }
    }
 
    printf("%d %d %d %d", max1, max2, max3, max4);
}
cs

단순무식하게 했다.

20x20 격자이니 2차원 배열로 20x20 공간을 만들었다.

각 방향마다 최대값을 구해서 max에 저장하고, max값을 출력해 눈으로 최대값을 확인했다.