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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdbool.h>
#define QUEUE_CAP 128
#define CHILDREN_CAP 128
#define ARR_SIZE(a) (sizeof(a)/sizeof(*a))
// #define FILENAME "sample.txt"
#define FILENAME "input.txt"
// #define PART1
#define PART2
#define NUMS(X) \
X(1, 1, 177622) \
X(2, 2, 177623) \
X(3, 3, 177624) \
X(4, 4, 177625) \
X(5, 5, 177626) \
X(6, 6, 177627) \
X(7, 7, 177628) \
X(8, 8, 177629) \
X(9, 9, 177630) \
#define STRS(X) \
X(one, 1, 193501607) \
X(two, 2, 193507359) \
X(three, 3, 210728981597) \
X(four, 4, 6385231329) \
X(five, 5, 6385224815) \
X(six, 6, 193505817) \
X(seven, 7, 210727692230) \
X(eight, 8, 210711216854) \
X(nine, 9, 6385512047) \
#define TO_STR_ARR(s, v, h) #s,
#define TO_CASE(s, v, h) \
case h: \
if(num_str[0] == 0) { \
num_str[0] = #v[0]; \
num_str[1] = #v[0]; \
} else { \
num_str[1] = #v[0]; \
} \
break;
// https://www.cse.yorku.ca/~oz/hash.html
unsigned long hash(char *str)
{
unsigned long hash = 5381;
int c;
while ((c = *str++))
hash = ((hash << 5) + hash) + c;
return hash;
}
// https://en.wikipedia.org/wiki/Aho%E2%80%93Corasick_algorithm
typedef struct trie_node {
struct trie_node *parent;
struct trie_node *children[CHILDREN_CAP];
struct trie_node *suffix;
bool end;
} trie;
trie *trie_init(char **dictionary, size_t nwords);
void trie_search(trie *root, char *str, void (*callback)(char *str, size_t len));
void trie_free(trie *root);
void trie_print(trie *root);
size_t sum = 0;
char num_str[3] = {0};
void handle_match(char *str, size_t len)
{
char s[len+1]; s[len] = '\0';
memcpy(s, str, len);
switch(hash(s)) {
NUMS(TO_CASE)
#ifdef PART2
STRS(TO_CASE)
#endif
default:
fprintf(stderr, "bad hash: %lu (of str %s)", hash(s), s);
}
}
int main(void)
{
char *dictionary[] = {
NUMS(TO_STR_ARR)
#ifdef PART2
STRS(TO_STR_ARR)
#endif
};
trie *root = trie_init(dictionary, ARR_SIZE(dictionary));
trie_print(root);
FILE *fp = fopen(FILENAME, "r");
if(!fp) {
perror("fopen: failed");
return 1;
}
char line[256];
while(fgets(line, sizeof(line), fp)) {
trie_search(root, line, handle_match);
sum += atoi(num_str);
num_str[0] = 0; num_str[1] = 0;
}
fclose(fp);
printf("Sum: %ld\n", sum);
trie_free(root);
return 0;
}
static trie *trie_find_suffix(trie *node, size_t idx);
static void trie_set_suffix(trie *node, size_t idx);
static void trie_traverse(trie *parent, void (*callback)(trie *node, size_t idx));
static void trie_add_pattern(trie *node, char *pattern);
trie *trie_init(char **patterns, size_t nwords)
{
trie *root = malloc(sizeof(trie));
memset(root, 0, sizeof(trie));
// generate the basic trie
for(size_t i = 0; i < nwords; i++) {
trie_add_pattern(root, patterns[i]);
}
// calculate suffix links
trie_traverse(root, trie_set_suffix);
return root;
}
void trie_search(trie *root, char *str, void (*callback)(char *str, size_t len))
{
trie *node = root;
for(size_t i = 0; i < strlen(str)+1; i++) {
if(node->children[(size_t)str[i]] != NULL) {
node = node->children[(size_t)str[i]];
continue;
}
if(node->end) {
int len = 0; trie *tmp = node;
while(tmp->parent != NULL) {
tmp = tmp->parent;
len++;
}
callback(&str[i-len], len);
}
if(node->suffix == NULL) continue;
node = node->suffix;
i--; continue;
}
}
void trie_free(trie *root)
{
for(int i = 0; i < CHILDREN_CAP; i++)
if(root->children[i] != NULL) {
trie_free(root->children[i]);
}
free(root);
}
static void trie_print_child(trie *root, trie *node, size_t depth)
{
for(int i = 0; i < CHILDREN_CAP; i++) {
if(node->children[i] != NULL) {
for(size_t i = 0; i < depth; i++) printf(" ");
printf("%c (%p) -> (%p) %s\n", i, (void *)node->children[i],
(void *)((node->children[i]->suffix == root) ?
0 : node->children[i]->suffix),
(node->children[i]->end ? "END" : ""));
trie_print_child(root, node->children[i], depth+2);
}
}
}
void trie_print(trie *root)
{
printf("ROOT (%p)\n", (void *)root);
trie_print_child(root, root, 2);
}
static trie *trie_find_suffix(trie *node, size_t idx)
{
if(node->suffix == NULL) return node; // root
if(node->suffix->children[idx] != NULL) {
return node->suffix->children[idx];
} else {
return trie_find_suffix(node->suffix, idx);
}
}
static void trie_set_suffix(trie *node, size_t idx)
{
node->suffix = trie_find_suffix(node->parent, idx);
}
static void trie_traverse(trie *root, void (*callback)(trie *node, size_t idx))
{
// breadth-first traversal
trie *queue[QUEUE_CAP] = {0};
size_t queue_start = 0, queue_end = 0;
queue[queue_end++] = root;
while(queue_start != queue_end) {
trie *parent = queue[queue_start++ % QUEUE_CAP];
for(size_t i = 0; i < CHILDREN_CAP; i++)
if(parent->children[i] != NULL) {
callback(parent->children[i], i);
queue[queue_end++ % QUEUE_CAP] = parent->children[i];
}
}
}
static void trie_add_pattern(trie *node, char *pattern)
{
if(pattern[0] == '\0') {
node->end = true;
return;
}
if(node->children[(size_t)pattern[0]] == NULL) {
trie *child = malloc(sizeof(trie));
memset(child, 0, sizeof(trie));
child->parent = node;
node->children[(size_t)pattern[0]] = child;
}
trie_add_pattern(node->children[(size_t)pattern[0]], &pattern[1]);
}
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