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#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#define ROUNDUP(x,y) ((((x)+(y)-1)/(y))*(y))
#define BIT_SET(set, d) \
( (void) ( set[d >> 3] |= (1 << (d & 7)) ) )
#define BIT_ISSET(set, d) \
(!(! ( set[d >> 3] & (1 << (d & 7)) ) ))
int ANY_BITS_SET(unsigned char *set, size_t bytes)
{
size_t i;
for (i = 0; i < bytes; i++)
if (set[i] != 0)
return 1;
return 0;
}
typedef __uint32_t art_id;
static int
cmpstring_p_pp(const void *p1, const void *p2)
{
return strcasecmp((char * const) p1, * (char * const *) p2);
}
int main(int argc, char **argv)
{
FILE *in_file;
FILE *out_file;
char **title = NULL;
art_id titles;
art_id titles_read = 0;
art_id **linki;
art_id *linkis;
char **cur_title;
art_id title_id;
art_id cur_dist;
art_id i;
unsigned char *titles_seen;
unsigned char *titles_prev_round;
unsigned char *titles_this_round;
size_t titles_bitfield_len;
if (argc < 2) {
printf("Supply article name to look up articles linking to it.\n");
return 1;
}
/*
* Read all incoming links into memory
*/
in_file = fopen("links-incoming.bin", "rb");
fread(&titles, sizeof(titles), 1, in_file);
linki = malloc(titles * sizeof(art_id*));
linkis = malloc(titles * sizeof(art_id));
for (i = 0; i < titles; i++) {
art_id j;
fread(&linkis[i], sizeof(linkis[i]), 1, in_file);
//printf("linkis[%zd] = %zd\n", i, linkis[i]);
linki[i] = malloc(linkis[i] * sizeof(linki[i][0]));
j = fread(linki[i], sizeof(linki[i][0]), linkis[i], in_file);
assert(j == linkis[i]);
//for (j = 0; j < linkis[i]; j++) {
// fread(&linki[i][j], sizeof(linki[i][j]), 1, in_file);
//}
}
printf("Incoming links read (%zd bytes).\n", ftell(in_file));
fclose(in_file);
/*
* Read all titles into memory
*/
title = malloc(titles * sizeof(title[0]));
in_file = fopen("titles-sorted.txt", "r");
while (!feof(in_file)) {
char *in_line = NULL;
ssize_t in_line_len = 0;
size_t zero = 0;
in_line_len = getline(&in_line, &zero, in_file);
/* Ignore empty lines and errors */
if (in_line_len < 2) {
continue;
}
/* Delete trailing newline */
in_line[in_line_len - 1] = '\0';
title[titles_read] = in_line;
titles_read++;
}
fclose(in_file);
printf("Titles read.\n");
/* Look up article ID */
cur_title = bsearch(argv[1], title,
titles, sizeof(title[0]),
cmpstring_p_pp);
if (!cur_title) {
printf("TITLE NOT FOUND: %s\n", argv[1]);
return 1;
}
title_id = cur_title - title;
#if 0
/* Print first degree incoming edges */
printf("Article %zd (%s) is linked from %zd articles:\n", title_id, title[title_id], linkis[title_id]);
for (i = 0; i < linkis[title_id]; i++) {
art_id x = linki[title_id][i];
printf(" %s\n", title[x]);
}
#endif
printf("\n\n\n\nBuilding table of distances...\n\n");
titles_bitfield_len = ROUNDUP(titles / 8, sizeof(size_t));
titles_seen = calloc(titles_bitfield_len, 1);
titles_prev_round = NULL;
titles_this_round = calloc(titles_bitfield_len, 1);
cur_dist = 0;
BIT_SET(titles_seen, title_id);
BIT_SET(titles_this_round, title_id);
while (ANY_BITS_SET(titles_this_round, titles_bitfield_len)) {
art_id i;
cur_dist++;
printf("Checking distance %d\n", cur_dist);
free(titles_prev_round); /* free is safe to call on NULL */
titles_prev_round = titles_this_round;
titles_this_round = calloc(titles_bitfield_len, 1);
for (i = 0; i < titles; i++) {
int j;
if (!BIT_ISSET(titles_prev_round, i))
continue;
for (j = 0; j < linkis[i]; j++) {
art_id x = linki[i][j];
BIT_SET(titles_this_round, x);
}
}
for (i = 0; i < titles_bitfield_len; i++) {
titles_this_round[i] &= ~titles_seen[i];
titles_seen[i] |= titles_this_round[i];
}
}
/* Result is in titles_prev_round */
cur_dist -= 1;
printf("\n\n\nThe articles with the distance of %zd are:\n\n", cur_dist);
for (i = 0; i < titles; i++) {
if (BIT_ISSET(titles_prev_round, i)) {
printf(" %s\n", title[i]);
}
}
return 0;
}
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