KMP字符串匹配算法实现

kmp字符串匹配算法C++代码实现

</pre><pre name="code" class="cpp">#ifndef __H_KMP_H__
#define __H_KMP_H__
#include <string>

//获得next数组
int _fill_next_array(char* comp, int len, int* next)
{
	int i = 0;
	int j = -1;
	next[0] = -1;
	while(i < len - 1)
	{
		if(j == -1 || comp[i] == comp[j])
		{
			++i;
			++j;
			if(comp[i] != comp[j])
			{
				next[i] = next[j];
			}else{
				next[i] = j;
			}
		}else{
			j = next[j];
		}
	}
	return 0;
}

//外部接口，返回一个字符串是否包含另一个字符串
bool is_contain_substring(char* src, char* comp)
{
	if((NULL == src && NULL != comp) || (NULL != src && NULL == comp))
		return false;
	int len1 = strlen(src);
	int len2 = strlen(comp);
	if(len1 < len2)
		return false;

	int* next = new int[len2];
	_fill_next_array(comp, len2, next);
	int j = 0;
	for(int i=0; i<len1; ++i)
	{
		if(src[i] == comp[j])
		{
			j++;
		}else{
			j = next[j]+1;
			if(src[i] == comp[j])
			{
				j++;
			}
		}

		if(j == len2)
			return true;
	}

	return false;
}

#endif

调用：

#include "KMP.h"

int main()
{
	std::cout << is_contain_substring("abcdabcabcdeabccba", "abcde") << std::endl;
	return 0;
}