95 lines
2.4 KiB
C
95 lines
2.4 KiB
C
/* NOTE: This problem is a significantly more challenging version of Problem 81.
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*
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* In the 5 by 5 matrix below, the minimal path sum from the top left to the bottom right, by moving left, right, up, and down,
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* is indicated in bold red and is equal to 2297.
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*
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* *131* 673 *234* *103* *18*
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* *201* *96* *342* 965 *150*
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* 630 803 746 *422* *111*
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* 537 699 497 *121* 956
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* 805 732 524 *37* *331*
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*
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* Find the minimal path sum, in matrix.txt, a 31K text file containing a 80 by 80 matrix,
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* from the top left to the bottom right by moving left, right, up, and down.*/
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#define _POSIX_C_SOURCE 199309L
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <limits.h>
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#include "projecteuler.h"
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int main(int argc, char **argv)
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{
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int i, j, dist;
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int **matrix, **distances;
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double elapsed;
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struct timespec start, end;
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FILE *fp;
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clock_gettime(CLOCK_MONOTONIC, &start);
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if((fp = fopen("matrix.txt", "r")) == NULL)
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{
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fprintf(stderr, "Error while opening file %s\n", "matrix.txt");
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return 1;
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}
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if((matrix = (int **)malloc(80*sizeof(int *))) == NULL ||
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(distances = (int **)malloc(80*sizeof(int *))) == NULL)
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{
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fprintf(stderr, "Error while allocating memory\n");
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return 1;
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}
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for(i = 0; i < 80; i++)
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{
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if((matrix[i] = (int *)malloc(80*sizeof(int))) == NULL ||
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(distances[i] = (int *)malloc(80*sizeof(int))) == NULL)
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{
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fprintf(stderr, "Error while allocating memory\n");
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return 1;
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}
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}
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for(i = 0; i < 80; i++)
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{
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for(j = 0; j < 80; j++)
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{
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fscanf(fp, "%d,", &matrix[i][j]);
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}
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}
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fclose(fp);
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/* Use Dijkstra's algorithm to find the minimum path.*/
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if(dijkstra(matrix, distances, 80, 80, 1, 1, 0) == -1)
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{
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fprintf(stderr, "Error! Dijkstra function returned -1\n");
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return 1;
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}
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dist = distances[79][79];
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for(i = 0; i < 80; i++)
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{
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free(matrix[i]);
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free(distances[i]);
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}
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free(matrix);
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free(distances);
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clock_gettime(CLOCK_MONOTONIC, &end);
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elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;
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printf("Project Euler, Problem 83\n");
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printf("Answer: %d\n", dist);
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printf("Elapsed time: %.9lf seconds\n", elapsed);
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return 0;
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}
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