KMP算法代码

#ifndef KMP_H_H
#define OK	0
#define	ERROR	-1
#define MAX_LENGTH	255
typedef unsigned char SString[MAX_LENGTH + 1];	//第0个位置存放串的长度
int sstr_assign(SString, const char*);
int sstr_print(SString);
int print_nextval(SString, int*, int);
void get_nextval(SString, int*);
int get_next(SString, int*);
int index_KMP(SString, SString, int, int*);
#endif

#include<stdio.h>
#include<stdlib.h>
#include"KMP.h"

//产生一个SString类型的串，其值等于sstr
int sstr_assign(SString T, const char *sstr)
{
int ix = 0;
while(sstr[ix] != '/0')
{
T[ix + 1] = sstr[ix++];
//如果空间耗尽，则不再复制。
if(ix == MAX_LENGTH)
break;
}
//保存串的长度
T[0] = ix;
return OK;
}

int sstr_print(SString T)
{
int cnt = T[0];
int ix = 1;
while(cnt-- > 0)
{
printf("%c",T[ix++]);
}
printf("/n");
return OK;
}

void get_nextval(SString T, int *nextval)
{
int i = 1;
int j = 0;
nextval[1] = 0;
while(i < T[0])
{
if(0 == j || T[i] == T[j])
{
i++;
j++;
if(T[i] != T[j])
{
nextval[i] = j;
}
else
nextval[i] = nextval[j];
}
else
j = nextval[j];
}
}

int get_next(SString T, int *next)
{
int i = 1;
int j = 0;
next[1] = 0;
while(i < T[0])
{
if(0 == j || T[i] == T[j])
{
i++;
j++;
next[i] = j;
}
else
j = next[j];
}
return OK;
}

int index_KMP(SString T, SString S, int pos, int *next)
{
if(pos < 1 || pos > T[0]
|| 0 == T[0] || 0 == S[0])
return ERROR;
int ix = pos;
int jx = 1;
while(ix <= T[0] && jx <= S[0])
{
if(jx == 0 || T[ix] == S[jx])
{
ix++;
jx++;
}
else
jx = next[jx];
}
if(jx > S[0])
return ix - S[0];
return OK;
}

int print_nextval(SString T, int *nextval, int n)
{
for(int i = 1 ; i <= n ; i++)
printf("%3d", i);
printf("/n");
for(i = 1 ; i <= n ; i++)
printf("%3c", T[i]);
printf("/n");
for(i = 1 ; i <= n ; i++)
printf("%3d", nextval[i]);
printf("/n");
return OK;
}