69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
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#include <malloc.h>
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#include <string.h>
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#define CHUNK 5
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int *create_lps(char *pattern, int pattern_len, int *lps) {
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int last_matched_char = 1;
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int last_prefix_char = 0;
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lps[0] = 0;
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while (last_matched_char < pattern_len) {
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if (pattern[last_matched_char] == pattern[last_prefix_char]) {
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lps[last_matched_char] = last_prefix_char + 1;
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last_matched_char++;
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last_prefix_char++;
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} else if (last_prefix_char != 0)
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// check if matches the previous prefix
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last_prefix_char = lps[last_prefix_char - 1];
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else {
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// if there isn't a prefix restart from the begin
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lps[last_matched_char] = 0;
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last_matched_char++;
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}
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}
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return lps;
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}
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int *search_pattern(char *text, char *pattern, int *lps, int *match_number, int *residue) {
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int size = CHUNK;
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int *matches = (int *) malloc(sizeof(int) * size);
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int text_index = 0;
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int pattern_index = 0;
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int text_len = strlen(text);
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int pattern_len = strlen(pattern);
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while (text_index < text_len) {
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// char matches
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if (text[text_index] == pattern[pattern_index]) {
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text_index++;
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pattern_index++;
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// full match found
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if (pattern_index == pattern_len) {
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// growth array if full
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if (*match_number == size) {
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size *= 2;
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matches = (int *) realloc(matches, size * sizeof(int));
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}
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matches[*match_number] = text_index - pattern_len;
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*match_number = *match_number + 1;
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pattern_index = lps[pattern_index - 1];
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}
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// char not matches on first char
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} else if (pattern_index == 0) {
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text_index++;
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} else {
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pattern_index = lps[pattern_index - 1];
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}
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}
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*residue = pattern_index;
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return matches;
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}
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