Boyer-Moore

#define R 256
 
void badChar(const char *p, int m, int last[R]) {
    for (int c = 0; c < R; c++) last[c] = -1;
    for (int i = 0; i < m; i++)
        last[(int)p[i]] = i;
}
 
void boyerMoore(const char *t, const char *p) {
    int n = strlen(t), m = strlen(p);
    int last[R];
    badChar(p, m, last);
 
    int s = 0;
    while (s <= n - m) {
        int j = m - 1;
        while (j >= 0 && p[j] == t[s + j])
            j--;
        if (j < 0) {
            printf("found at %d\n", s);
            s += 1;
        } else {
            int shift = j - last[(int)t[s + j]];
            s += shift > 1 ? shift : 1;
        }
    }
}