104 lines
2.5 KiB
C
104 lines
2.5 KiB
C
/* Using names.txt, a 46K text file containing over five-thousand first names, begin by sorting it into alphabetical order.
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* Then working out the alphabetical value for each name, multiply this value by its alphabetical position in the list to obtain a name score.
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*
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* For example, when the list is sorted into alphabetical order, COLIN, which is worth 3 + 15 + 12 + 9 + 14 = 53, is the 938th name in the list.
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* So, COLIN would obtain a score of 938 × 53 = 49714.
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*
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* What is the total of all the name scores in the file?*/
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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 <string.h>
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#include <time.h>
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#include "projecteuler.h"
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int compare(void *string1, void *string2);
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int main(int argc, char **argv)
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{
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FILE *fp;
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int i, j, n, len, score, sum = 0;
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double elapsed;
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char *line, **names;
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struct timespec start, end;
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clock_gettime(CLOCK_MONOTONIC, &start);
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if((fp = fopen("names.txt", "r")) == NULL)
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{
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fprintf(stderr, "Error while opening file %s\n", "names.txt");
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return 1;
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}
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fscanf(fp, "%ms", &line);
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fclose(fp);
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len = strlen(line);
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n = 1;
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/* Count the names in the file.*/
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for(i = 0; i < len; i++)
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{
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if(line[i] == ',')
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{
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n++;
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}
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}
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if((names = (char **)malloc(n*sizeof(char *))) == 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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/* Save each name in a string.*/
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names[0] = strtok(line, ",\"");
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for(i = 1; i < n; i++)
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{
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names[i] = strtok(NULL, ",\"");
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}
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/* Use quick_sort algorithm implemented in projecteuler.c to sort the names.*/
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quick_sort((void **)names, 0, n-1, compare);
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/* Calculate the score of each name an multiply by its position.*/
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for(i = 0; i < n; i++)
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{
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len = strlen(names[i]);
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score = 0;
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for(j = 0; j < len; j++)
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{
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score += names[i][j] - 'A' + 1;
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}
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score *= (i + 1);
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sum += score;
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}
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free(line);
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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 22\n");
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printf("Answer: %d\n", sum);
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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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/* Function to compare two strings, to pass to the quick_sort function.*/
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int compare(void *string1, void *string2)
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{
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char *s1, *s2;
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s1 = (char *)string1;
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s2 = (char *)string2;
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return strcmp(s1, s2);
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}
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