KMP算法实现

依照KMP实现的算法，附带测试用例。

#include <algorithm>
#include<iostream>
#include<iterator>
#include <string>
#include <vector>
#include <cassert>
#include <cstring>
using namespace std;


/**计算next***/
void kmp_next(char *pattern,int *next)
{
    int i = 0 ;
    int j = next[0] = -1;
    while(pattern[i]!= '\0')
    {
        if((j == -1) || (pattern[i] == pattern[j]))
            next[++i]= ++j;
        else
            j = next[j];
    }
}
/**计算next_val***/
void kmp_next_val(char *pattern,int *next_val)
{
    int i = 0;
    int j = next_val[0] = -1;
    while(pattern[i]!='\0')
    {
        if((j == -1)|| (pattern[i] == pattern[j]))
            if(pattern[++i] != pattern[++j])
                next_val[i] = j;
            else
                next_val[i] = next_val[j];
        else
            j = next_val[j];
    }
} 
/****match  是长串**

*****pattern 是模式串**/
int kmp_match(char *match,char *pattern)
{
    int m = strlen(pattern);

    int next[m];
    int i,j; 
    /**打印表格**/
    for(i = 0; i < m ; ++i)
        cout<<i<<'\t';
    cout<<endl;
    kmp_next(pattern,next);
    copy(next,next+m,ostream_iterator<int > (cout,"\t"));    
    cout<<endl;
    kmp_next_val(pattern,next);
    copy(next,next+m,ostream_iterator<int > (cout,"\t"));    
    cout<<endl;

    i = j = 0;
    while((match[i]!='\0')&&(pattern[j]!='\0'))
    {
        if((j == -1)||(match[i] == pattern[j]))
            ++i,++j;
        else
            j = next[j];
        
    }
    return j == m?(i -j):-1;
}


int main(int argc,char *argv[])
{
    char src[max_size];
    char dst[max_size];
    int m ,n;
    int position = 0;
    while(cin >> src >> dst)
    {
        position = kmp_match(src,dst);

        if(position != -1)
            cout<<"find at \t "<<position<<endl;
        else
            cout<<"not a substring\n";

        cout<<"--------end----------\n\n";
    }
    return 0;
}