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authorAlexander Pickering <alexandermpickering@gmail.com>2018-10-25 12:08:54 -0400
committerAlexander Pickering <alexandermpickering@gmail.com>2018-10-25 12:08:54 -0400
commitb9899c6cbe2f694c9db36e9d4e15c532d10b546f (patch)
tree248564d6bd22dd6f11459a51f73a144ae91756fc /src/kmp.c
parentd416a80324225d0c64c5021e74773a2e768de73a (diff)
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Started refactoring code
Added a src/ and build/ directory Added a include/ directory Included file is smaller
Diffstat (limited to 'src/kmp.c')
-rw-r--r--src/kmp.c70
1 files changed, 70 insertions, 0 deletions
diff --git a/src/kmp.c b/src/kmp.c
new file mode 100644
index 0000000..d5923bf
--- /dev/null
+++ b/src/kmp.c
@@ -0,0 +1,70 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "kmp.h"
+
+/* KMP implementation stolen from Github user cagdass*/
+
+int* init_array(int size) {
+ int* arr = (int*)malloc(size * sizeof(int));
+ int i;
+ for(i = 0; i < size; i++) {
+ arr[i] = 0;
+ }
+
+ return arr;
+}
+
+int kmp(char* t,size_t tlen, char* p,size_t plen) {
+ int m = plen;
+ int n = tlen;
+
+ int* f = init_array(m); // Failure function values.
+ int i = 0;
+ int j = 0;
+
+ while (i < n) {
+ if (t[i] == p[j]) {
+ if (j == m - 1) {
+ return i - j;
+ }
+ else {
+ i += 1;
+ j += 1;
+ }
+ }
+ else {
+ if (j > 0) {
+ j = f[j-1];
+ }
+ else {
+ i += 1;
+ }
+ }
+ }
+
+ return -1;
+}
+
+void failure(char* p, int* f) {
+ f[0] = 0;
+ int i = 1;
+ int j = 0;
+
+ int m = strlen(p);
+
+ while (i < m) {
+ if (p[i] == p[j]) {
+ f[i] = j + 1; // j+1 matches up to the current character.
+ i += 1;
+ j += 1;
+ }
+ else if (j > 0) {
+ j = f[j - 1];
+ }
+ else {
+ f[i] = 0;
+ i += 1;
+ }
+ }
+}