Tuesday 18 June 2013

PROJECT EULER SOLUTION # 11

Solution to problem number 11 of Project Euler.
Question # 11
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 any direction (up, down, left, right, or diagonally) in the 20×20 grid?

Solution # 11
/*********************************************************************/
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>

long find_max(int **);

int main()
{
                FILE *f;
                int **arr,i=0,j;
                arr=(int **)malloc(sizeof(int*)*20);
                for(i=0;i<20;i++)
                                arr[i]=(int *)malloc(sizeof(int)*20);

                f=fopen("D:/b.txt","r");
                if(f)
                                for(i=0;i<20;i++)
                                                for(j=0;j<20;j++)
                                                                fscanf(f,"%d",&arr[i][j]);             
                else
                                printf("file operation not successful\n");

                printf("Answer = %ld\n",find_max(arr));
               
                system("pause");
}


long find_max(int **arr)
{
                int i,j,k;
                long product,max=0;
                for(i=0;i<20;i++)
                                for(j=0;j<20;j++)
                                {
                                                /*checking for horizontal sequence*/
                                                product=1;
                                                for(k=0;k<4;k++)
                                                {
                                                                if(j+k<20)
                                                                {
                                                                                product*=arr[i][j+k];
                                                                }
                                                }
                                                if(product>max)
                                                                max=product;
                                               
                                                /*checking for vertical sequence*/
                                                product=1;
                                                for(k=0;k<4;k++)
                                                {
                                                                if(i+k<20)
                                                                {
                                                                                product*=arr[i+k][j];
                                                                }
                                                }
                                                if(product>max)
                                                                max=product;
                                               
                                                product=1;
                                                for(k=0;k<4;k++)
                                                {
                                                                if( (i+k<20) && (j+k<20) )
                                                                {
                                                                                product*=arr[i+k][j+k];
                                                                }
                                                }
                                                if(product>max)
                                                                max=product;

                                                product=1;
                                                for(k=0;k<4;k++)
                                                {
                                                                if( (i+k<20) && (j-k>0) )
                                                                {
                                                                                product*=arr[i+k][j-k];
                                                                }
                                                }
                                                if(product>max)
                                                                max=product;
                                               

                                }
                                return max;
}
/*********************************************************************/



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