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This commit is contained in:
David Makray
2020-09-28 00:53:04 -04:00
parent 4a1183c2e6
commit 4b2eb081cd
1 changed files with 7 additions and 3 deletions
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10
searching/knuth-moris-pratt.c
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@@ -8,7 +8,7 @@ int knuth_moris_pratt(char*, char*);
void main()
{
puts("Knuth-Moris-Pratt Algorithm\n");
char* alphabet = "abcdefghijklmnopqrstuvwxyz";
check_kmp(alphabet, "mno", 12);
check_kmp(alphabet, "abc", 0);
@@ -17,6 +17,7 @@ void main()
check_kmp(text, "bbccc", 4);
}
//Validate the Knuth-Moris-Pratt algorithm
void check_kmp(char* text, char* search_string, int expect)
{
printf("Find: '%s' in:\n%s\n", search_string, text);
@@ -43,6 +44,7 @@ void check_kmp(char* text, char* search_string, int expect)
puts("\nExpected result found. Test is valid.\n");
}
//Knuth-Moris-Pratt text search algorithm
int knuth_moris_pratt(char* text, char* search_string)
{
int text_length = strlen(text);
@@ -54,6 +56,7 @@ int knuth_moris_pratt(char* text, char* search_string)
memset(pexamine_array, 0, search_string_length);
char* pexamine = pexamine_array;
//Calculate the search string's failure offset array.
int look_up = 0, iterator = 1;
while (iterator < search_string_length)
{
@@ -69,6 +72,7 @@ int knuth_moris_pratt(char* text, char* search_string)
*pexamine = (char)look_up;
}
//Find search string. Partial matches are skipped by the calculated amount in the failure offset array.
iterator = 0;
int sampler = 0;
while (iterator < text_length)
@@ -78,7 +82,7 @@ int knuth_moris_pratt(char* text, char* search_string)
if (sampler == search_string_length - 1)
{
free(pexamine_array);
return iterator - search_string_length + 1;
return iterator - search_string_length + 1; //Search string is found.
}
sampler++;
}
@@ -91,5 +95,5 @@ int knuth_moris_pratt(char* text, char* search_string)
}
free(pexamine_array);
return -1;
return -1; //Search string is not found.
}