克努特 - 莫里斯 - 普拉特算法的C语言实现

/*     Copyright 2011 Shao-Chuan Wang <shaochuan.wang AT gmail.com>         Permission is hereby granted, free of charge, to any person obtaining a copy      of this software and associated documentation files (the "Software"), to deal      in the Software without restriction, including without limitation the rights      to use, copy, modify, merge, publish, distribute, sublicense, and/or sell      copies of the Software, and to permit persons to whom the Software is      furnished to do so, subject to the following conditions:         The above copyright notice and this permission notice shall be included in      all copies or substantial portions of the Software.         THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR      IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,      FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE      AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,      OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN      THE SOFTWARE.  */  #include <stdio.h>  #include <stdlib.h>  #include <string.h>     int *compute_prefix_function(char *pattern, int psize)  {      int k = -1;      int i = 1;      int *pi = malloc(sizeof(int)*psize);      if (!pi)          return NULL;         pi[0] = k;      for (i = 1; i < psize; i++) {          while (k > -1 && pattern[k+1] != pattern[i])              k = pi[k];          if (pattern[i] == pattern[k+1])              k++;          pi[i] = k;      }      return pi;  }     int kmp(char *target, int tsize, char *pattern, int psize)  {      int i;      int *pi = compute_prefix_function(pattern, psize);      int k = -1;      if (!pi)          return -1;      for (i = 0; i < tsize; i++) {          while (k > -1 && pattern[k+1] != target[i])              k = pi[k];          if (target[i] == pattern[k+1])              k++;          if (k == psize - 1) {              free(pi);              return i-k;          }      }      free(pi);      return -1;  }     int main(int argc, const char *argv[])  {      char target[] = "ABC ABCDAB ABCDABCDABDE";      char *ch = target;      char pattern[] = "ABCDABD";      int i;         i = kmp(target, strlen(target), pattern, strlen(pattern));      if (i >= 0)          printf("matched @: %s\n", ch + i);      return 0;  }  /** end of http://code.activestate.com/recipes/577908/ }}} */