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/*
Challenge 005
Challenge #2
Write a program to find the sequence of characters that has the most anagrams.
create a hash of all words in dictionary where key is sorted list of letters
therefore two anagrams have the same key
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "uthash.h"
#define MAX_WORD 1024
struct anagram {
char* key;
int count;
UT_hash_handle hh;
};
struct anagram* anagrams = NULL;
void* check_mem(void* p) {
if (!p) {
fputs("Out of memory", stderr);
exit(EXIT_FAILURE);
}
return p;
}
void trim(char* str) {
int len = strlen(str);
while (len > 0 && isspace(str[len - 1]))
str[--len] = '\0';
}
void strtolower(char* str) {
for (char* p = str; *p; p++)
*p = tolower(*p);
}
int compare_char(const void* a, const void* b) {
return *(const char*)a - *(const char*)b;
}
void word_key(char* key, const char* word) {
strcpy(key, word);
qsort(key, strlen(key), 1, compare_char);
}
int compare_anagrams(struct anagram* a, struct anagram* b) {
return strcmp(a->key, b->key);
}
int main() {
int max_anagrams = 0;
char key[MAX_WORD], line[MAX_WORD];
struct anagram* anagram, *tmp;
FILE* fp = fopen("words.txt", "r");
if (!fp) return EXIT_FAILURE;
// collect anagram keys and count occurrences
while (fgets(line, MAX_WORD, fp)) {
trim(line);
strtolower(line);
word_key(key, line);
HASH_FIND_STR(anagrams, key, anagram);
if (!anagram) {
anagram = check_mem(malloc(sizeof(struct anagram)));
anagram->key = check_mem(strdup(key));
anagram->count = 1;
HASH_ADD_KEYPTR(hh, anagrams, anagram->key, strlen(anagram->key), anagram);
}
else
anagram->count++;
if (max_anagrams < anagram->count)
max_anagrams = anagram->count;
}
fclose(fp);
// list anagrams
HASH_SRT(hh, anagrams, compare_anagrams);
printf("Maximum of %d anagrams\n", max_anagrams);
for (anagram = anagrams; anagram != NULL; anagram = anagram->hh.next) {
if (anagram->count == max_anagrams)
printf("%s\n", anagram->key);
}
// free memory
HASH_ITER(hh, anagrams, anagram, tmp) {
HASH_DEL(anagrams, anagram);
free(anagram->key);
free(anagram);
}
return EXIT_SUCCESS;
}
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