终于看懂KMP算法了！
头文件HString.h：
/*HString.h*/
#ifndef HSTRING_H_INCLUDED
#define HSTRING_H_INCLUDED
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>
#define DefaultSize 30
typedef struct
{
char *ch; /*顺序串的存储数组*/
int maxSize; /*字符串存储数组的最大长度*/
int n; /*顺序串的实际长度*/
} HString;
#endif /*HSTRING_H_INCLUDED*/
头文件KMP.h：
/*KMP.h*/
#ifndef KMP_H_INCLUDED
#define KMP_H_INCLUDED
#include "HString.h"
void GetNext ( HString *P, int next[] );
int FastFind ( HString *T, HString *P, int next[ ] );
#endif /* KMP_H_INCLUDED*/源文件HString.c：
/*HString.c*/
#include "HString.h"
HString *initStr ( HString *s )/*串初始化*/
{
s->ch = ( char *) malloc ( ( DefaultSize+1 )*sizeof ( char ) ); /*动态分配*/
s->ch[0] = '\0';
s->maxSize = DefaultSize;
s->n = 0; /*串s的最大容量和当前长度*/
return s;
}
void createStr ( HString *s, char *init )/*从字符数组init构造串s*/
{
s->maxSize = DefaultSize;
s->ch = ( char *) malloc (( DefaultSize+1 )*sizeof ( char ));
s->n = strlen ( init );
strcpy ( s->ch, init );
}
void copyStr ( HString *s, HString *t )/*把串t复制给串s*/
{
s->maxSize = DefaultSize;
s->ch = ( char *) malloc ( ( DefaultSize+1 )*sizeof ( char ) );
s->n = t->n;
strcpy ( s->ch, t->ch );
}
HString *subStr ( HString *s, int pos, int len )/*在串s中连续取从pos开始的len个字符，
构成子串返回。若提取失败则函数返回NULL*/
{
HString *tmp = ( HString * )malloc( sizeof(HString) );
tmp->ch = ( char *) malloc ( ( DefaultSize+1 )*sizeof ( char ) );
tmp->maxSize = DefaultSize;
if ( pos < 0 || len < 0 || pos+len-1 >= s->maxSize ) /*参数不合理，返回空串*/
{
tmp->n = 0;
tmp->ch[0] = '\0';
}
else
{
if ( pos+len-1 >= s->n )
len = s->n-pos; /*若提取个数超出串尾，修改个数*/
for ( int i = 0, j = pos; i < len; i++, j++)
tmp->ch[i] = s->ch[j];
tmp->n = len;
tmp->ch[len] = '\0';
}
return tmp;
}
void concat ( HString *s, HString *t )
{
/*将串t复制到串s后，串t不变。若完全连接成功，函数返回true；若部分连接成功，或
连接不成功，函数返回false*/
if ( s->n+t->n <= s->maxSize )/*原空间可容纳连接后的串*/
{
for ( int i = 0; i < t->n; i++ )
s->ch[s->n+i] = t->ch[i];
s->n = s->n+t->n;
s->ch[s->n] = '\0';
}
else
{ /*原空间容不下连接后的串*/
char *tmp = s->ch;
s->maxSize = s->n+t->n; /*暂存原串数组，算新串数组大小*/
s->ch = ( char* ) malloc ( ( s->maxSize+1 )*sizeof ( char ) );
strcpy ( s->ch, tmp );
strcat ( s->ch, t->ch ); /*复制原串s数组, 连接串t数组*/
s->n = s->n+t->n;
free ( tmp );
}
}
char getChar ( HString *s, int i )/*提取串s的第i个字符*/
{
if ( i < 0 || i >= s->n )
{
printf ( "字符串下标超界!\n" );
return '\0';
}
return s->ch[i];
}
void printStr ( HString *s )
{
printf ("打印串长度s->n=%d, 最大长度=%d\n", s->n, s->maxSize);
for ( int i = 0; i < s->n; i++ )
if ( s->ch[i] == '\0' )
break;
else
printf ( "%c", s->ch[i] );
printf("\n");
}源文件KMP.c：
/*KMP.c*/
#include "KMP.h"
void GetNext ( HString *P, int next[] )
{
/*对模式串P, 计算next失配函数*/
int j = 0, k = -1;
next[0] = -1;
while ( j < P->n )/*计算next[j]*/
{
while ( k >= 0 && P->ch[j] != P->ch[k] )
k = next[k];
j++;
k++;
if ( P->ch[j] == P->ch[k] )
next[j] = next[k];
else
next[j] = k;
}
}
int FastFind ( HString *T, HString *P, int next[ ] )
{
/*在目标串T中寻找模式串P的匹配位置。若找到，则函数返回P在T中开始字符
下标，否则函数返回-1。数组nex存放P的失配函数next[j]值。*/
int j = 0, i = 0; /*串P与串T的扫描指针*/
while ( j < P->n && i < T->n ) /*对两串扫描*/
{
printf ( "i=%d, j=%d\n", i, j );
if ( j == -1 || P->ch[j] == T->ch[i] )
{
j++; /*对应字符匹配，比对位置加一*/
i++;
}
else
j = next[j]; /*第j位失配，找下一对齐位置*/
}
if ( j < P->n )
return -1; /*j未比完失配，匹配失败*/
else
return i-P->n; /*匹配成功*/
}源文件test.c：
/*test.c*/
/*
Name: 纯C语言基于堆式串实现KMP算法
Copyright: 2018
Author: 刁肥宅
Contact Author: 2046195761（QQ）、[email protected]（Email）
Date: 10/08/18 17:52
Description: 呜啦啦！唯爱小桃子~
*/
#include "KMP.h"
int main()
{
char A[] = {'H','e','f','e','i','U','n','i','v','e','r','s','i',
't','y','O','f','T','e','c','h','n','o','l','o','g','y','\0'};
char B[] = {'U','n','i','v','e','r','s','i','t','y','\0'};
HString *S1 = ( HString * )malloc( sizeof(HString) ),*S2 = ( HString * )malloc( sizeof( HString ) );
int Fail[DefaultSize];
int i,d;
for( i = 0;i < DefaultSize;i ++ )
Fail[i] = 0;
printf("Name: 纯C语言基于堆式串实现KMP算法\n");
printf("Copyright: 2018\nAuthor: 刁肥宅\n");
printf("Contact Author: 2046195761（QQ）、[email protected]（Email）\n");
printf("Date: 10/08/18 17:52\nDescription: 呜啦啦！唯爱小桃子~\n\n");
createStr( S1,A );
printStr( S1 );
createStr( S2,B );
printStr( S2 );
GetNext ( S2, Fail );
for ( i = 0; i < S2->n; i++ )
printf ( "%d ", Fail[i] );
printf("\n");
d = FastFind ( S1, S2, Fail );
if( d == -1 )
printf("匹配位置失败！\n");
else
printf("匹配位置为%d\n",d);
Sleep(1000 * 60);
return 0;
}晒一晒我美腻的小桃子：
程序运行截图如下：
