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feat: solution to project euler problem 11 #871

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cd5b949
Solution: project euler problem 11
Vipul-Cariappa Oct 7, 2021
db9a9e9
updates sol1.c
Vipul-Cariappa Oct 8, 2021
24341eb
updated sol1.c
Vipul-Cariappa Oct 8, 2021
55faf5e
Update project_euler/problem_11/sol1.c
Vipul-Cariappa Oct 9, 2021
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121 changes: 121 additions & 0 deletions project_euler/problem_11/sol1.c
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/**
* @file
* @brief [Problem 11](https://projecteuler.net/problem=11) solution
* @author [Vipul Cariappa](https://github.com/vipul-cariappa)
* @details
* Code to find the greatest product of four adjacent numbers in the same
* direction (up, down, left, right, or diagonally) in the given grid
*/

#include <stdio.h> // for IO operations

#define ARRAY_SIZE 20 // size of gird
typedef unsigned long long large; // To hold product of numbers

/**
* @brief Main function
* @returns 0 on exit
*/
int main()
{
int array[ARRAY_SIZE][ARRAY_SIZE] = {
{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},
};

// to store present largest number
large biggest = 0;
large tmp;

for (int i = 0; i < ARRAY_SIZE; i++)
{
for (int j = 0; j < ARRAY_SIZE; j++)
{
// calculating product and checking against prest biggest number
// row
if (j < ARRAY_SIZE - 4)
{
tmp = (large)array[i][j] * array[i][j + 1] * array[i][j + 2] *
array[i][j + 3];
if (tmp > biggest)
{
biggest = tmp;
}
}

// column
if (i < ARRAY_SIZE - 4)
{
tmp = (large)array[i][j] * array[i + 1][j] * array[i + 2][j] *
array[i + 3][j];
if (tmp > biggest)
{
biggest = tmp;
}
}

// diagonal (towards down left)
if ((i < ARRAY_SIZE - 4) && (j < ARRAY_SIZE - 4))
{
tmp = (large)array[i][j] * array[i + 1][j + 1] *
array[i + 2][j + 2] * array[i + 3][j + 3];
if (tmp > biggest)
{
biggest = tmp;
}
}

// diagonal (towards down right)
if ((j > 3) && (i < ARRAY_SIZE - 4))
{
tmp = (large)array[i][j] * array[i + 1][j - 1] *
array[i + 2][j - 2] * array[i + 3][j - 3];
if (tmp > biggest)
{
biggest = tmp;
}
}
}
}

printf("Largest Product: %llu\n", biggest);
return 0;
}