KMP模式匹配算法

 

 
#include<iostream>
using namespace std;

bool _Get_Nextvalue(char c_pattern_string[], int i_next_value[])
{
 int length = strlen(c_pattern_string);
 if (!c_pattern_string || !length)
  return false;
 i_next_value[ 0 ] = 0;
 int j = -1, i = 0;
 length--;
 while (i < length)
 {
  if (j == -1 || c_pattern_string[ i ] == c_pattern_string[ j ])
     if (c_pattern_string[ ++i ] == c_pattern_string[ ++j ])
     i_next_value[i] = i_next_value[j];
     else
     ++(i_next_value[i] = j);
  else
   --(j = i_next_value[j]);
 }//while
 return true;
}

int Index_KMP(char c_sourse_string[], char c_pattern[], int i_next_value[], int start_pos, int length_pattern)
{
 //c_sourse_string[]源串 c_pattern[]模式字符串
 int i = start_pos, j = 0, length = strlen(c_sourse_string);
 while (i < length && j < length_pattern)
 {
  if (j == -1 || c_sourse_string[ i ] == c_pattern[ j ])
  {
   i++;
   j++;
  }
  else
   --(j = i_next_value[j]);
 }
 if (j >= length_pattern) 
  return i - length_pattern;
 else
  return -1;
}

int main(void)
{
 char c_pattern_string1[] = "abaaasssaaaadfghaaaaa", c_pattern_string[] = "aaaaa";
 int length_str = strlen(c_pattern_string);
 int * i_next_value = new int [ length_str];
 _Get_Nextvalue(c_pattern_string, i_next_value);
 int i = Index_KMP(c_pattern_string1, c_pattern_string, i_next_value, 0, length_str); 
 if (i != -1)
 for (length_str = strlen(c_pattern_string1) ;i < length_str; i++)
  cout << c_pattern_string1[ i ] << " ";
 cout << endl;
 delete i_next_value;
 i_next_value = NULL;
 return 0;
}