BM算法实现源代码

void preBmBc(char *x, int m, int bmBc[]) {   int i;    for (i = 0; i < ASIZE; ++i)      bmBc[i] = m;   for (i = 0; i < m - 1; ++i)      bmBc[x[i]] = m - i - 1;}  void suffixes(char *x, int m, int *suff) {   int f, g, i;    suff[m - 1] = m;   g = m - 1;   for (i = m - 2; i >= 0; --i) {      if (i > g && suff[i + m - 1 - f] < i - g)         suff[i] = suff[i + m - 1 - f];      else {         if (i < g)            g = i;         f = i;         while (g >= 0 && x[g] == x[g + m - 1 - f])            --g;         suff[i] = f - g;      }   }} void preBmGs(char *x, int m, int bmGs[]) {   int i, j, suff[XSIZE];    suffixes(x, m, suff);    for (i = 0; i < m; ++i)      bmGs[i] = m;   j = 0;   for (i = m - 1; i >= 0; --i)      if (suff[i] == i + 1)         for (; j < m - 1 - i; ++j)            if (bmGs[j] == m)               bmGs[j] = m - 1 - i;   for (i = 0; i <= m - 2; ++i)      bmGs[m - 1 - suff[i]] = m - 1 - i;}  void BM(char *x, int m, char *y, int n) {   int i, j, bmGs[XSIZE], bmBc[ASIZE];    /* Preprocessing */   preBmGs(x, m, bmGs);   preBmBc(x, m, bmBc);    /* Searching */   j = 0;   while (j <= n - m) {      for (i = m - 1; i >= 0 && x[i] == y[i + j]; --i);      if (i < 0) {         OUTPUT(j);         j += bmGs[0];      }      else         j += MAX(bmGs[i], bmBc[y[i + j]] - m + 1 + i);   }}