Sunday, 2 November 2014

PROJECT EULER SOLUTION # 82

PROJECT EULER PROBLEM # 82
NOTE: This problem is a more challenging version of Problem 81.
The minimal path sum in the 5 by 5 matrix below, by starting in any cell in the left column and finishing in any cell in the right column, and only moving up, down, and right, is indicated in red and bold; the sum is equal to 994.
131
673
234
103
18
201
96
342
965
150
630
803
746
422
111
537
699
497
121
956
805
732
524
37
331
Find the minimal path sum, in matrix.txt (right click and 'Save Link/Target As...'), a 31K text file containing a 80 by 80 matrix, from the left column to the right column.


PROJECT EULER SOLUTION # 82

#include<stdio.h>
int mat[80][80],minimum[80][80],n;
int min2(int a,int b)
{
    return (a>b?b:a);
}
int min3(int a,int b,int c)
{
    return (a<b?(min2(a,c)):(min2(b,c)));
}

int main()
{
    int min,i,j;
    char temp;
    FILE *f;
    n=9;
    f=fopen("matrix.txt","r");
    if(f)
    {
        for(i=0;i<n;i++)
        {
            for(j=0;j<n-1;j++)
                fscanf(f," %d%c",&mat[i][j],&temp);
            fscanf(f,"%d",&mat[i][j]);
        }

        for(i=0;i<n;i++)
            minimum[i][0]=mat[i][0];
        for(i=1;i<n;i++)
        {
            j=0;
            minimum[j][i]=mat[j][i]+min2(minimum[j][i-1],minimum[j+1][i-1]+mat[j+1][i]);
            for(j=1;j<n;j++)
                minimum[j][i]=mat[j][i]+min2(minimum[j][i-1],minimum[j-1][i]);

            for(j=n-2;j>=0;j--)
                minimum[j][i]=min2(minimum[j+1][i]+mat[j][i],minimum[j][i]);
        }
        for(i=0;i<n;i++)
        {
            for(j=0;j<n;j++)
                printf("%d ",minimum[i][j]);
            printf("\n");
        }
        min=2147483647;
        for(i=0;i<n;i++)
            if(min>minimum[i][n-1])
                min=minimum[i][n-1];
        printf("answer = %d\n",min);
    }
    else
        printf("there is some error in opening the file\n");
    return 0;
}


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