【字符串】KMP匹配模板

char str1[1010];
char str2[1010];
int Next[1010];

void next_arr()
{
    int len = strlen(str2);
    Next[0] = -1;
    int k = -1;
    int j = 0;
    while (j < len - 1)
    {
        if (k == -1 || str2[j] == str2[k])
        {
            ++k;
            ++j;
            Next[j] = k;
        }
        else
            k = Next[k];
    }
}

int kmp_match()
{
    next_arr();
    int i=0,j=0;
    int len1=strlen(str1);
    int len2=strlen(str2);
    while(i<len1&&j<len2){
        if(j==-1||str1[i]==str2[j]){
            i++;
            j++;

        }
        else 
	    j=Next[j];
    }
    if(j == len2)
        return i - j; 
    return -1; 

}