八数码难题（转）

问题描述：
在3×3的棋盘上，摆着8个将牌，每个将牌都刻有1～8数码中的某个数码。棋盘中留有一个空格，允许其周围的某个将牌向空格移动，这样通过移动将牌就可以不断改变棋牌的布局。
请用计算机实现算法解决八数码问题：提供输入初始将牌布局和目标将牌布局的功能，在接收输入之后，输出移动的步骤（方式）。

/*
* =====================================================================================
*
* Filename: eightnum.c
*
* Description: 8数码问题（A算法）
*
* Version: 1.0
* Created: 2008-11-4 19:43:19
* Revision: none
* Compiler: gcc
*
* Author: MneeHNXM (Mnee), MneeHNXM@gmail.com
* Company: HeNan University
*
* =====================================================================================
*/
#include    <stdlib.h>
#include    <stdio.h>
typedef struct Node {
int num[9]; //棋盘状态
int deepth; //派生的深度 g(n)
int diffnum; //不在位的数目 h(n)
int value; //耗散值 f(n)=g(n)+h(n)
struct Node * pre;
struct Node * next;
struct Node * parent;
}numNode;                /* ---------- end of struct numNode ---------- */
int origin[9]; //棋盘初始状态
int target[9]; //棋盘目标状态
int numNode_num,total_step;
numNode *open,*close; //Open表和Close表
numNode *create_numNode()
{
return (numNode *)malloc(sizeof(numNode));
}
numNode *open_getfirst(numNode *head); //返回第一项，并从Open表中删除
void open_insert(numNode *head,numNode *item); //向Open表中按序插入新节点
void close_append(numNode *head,numNode *item); //向Close表中插入新节点
int expand(numNode *item); //扩展节点
int print_result(numNode *item); //打印结果
numNode *copy_numNode(numNode *orgin);
char isNewNode(numNode *open,numNode *close,int num[9]);
//是否在Open表或Close表中
void print_num(int num[9]); //打印棋盘状态
int diff(int num[9]); //求不在位棋子的个数
void init(); //初始化，获得棋盘初始状态和目标状态
void swap(int *a,int *b);
int operate(int num[],int op);
void free_list(numNode *head);
/*
* === FUNCTION ======================================================================
* Name: 主函數
* Description: 程序入口
* =====================================================================================
*/
int
main ( int argc, char *argv[] )
{
//初始化Open表和Close表
open=create_numNode();
close=create_numNode();
open->pre=open->next=close->pre=close->next=NULL;
init(); //由用户输入初始和目标状态
//初始化初始节点
numNode *p1;
p1=create_numNode();
p1->parent=NULL;
p1->deepth=0;
int i=0;
for ( i=0; i<9; i++)
{
p1->num[i]=origin[i];
}
open_insert(open,p1);
numNode_num=1;
p1=open_getfirst(open);
while (p1!=NULL)
{
close_append(close,p1);
if(expand(p1))
return EXIT_SUCCESS;
p1=open_getfirst(open);
}
printf("No solution!/n");
return EXIT_SUCCESS;
}                /* ---------- end of function main ---------- */
void
init ( )
{
while(1)
{
printf("Please input opriginal status:/nFor example:123456780 stands for/n"
"1    2    3/n"
"4    5    6/n"
"7    8    0/n");
char temp[10];
scanf("%s",&temp);
int i=0;
for ( i=0;i<9 && temp[i]-'0'>=0 && temp[i]-'0'<=8; i++)
{
origin[i]=temp[i]-'0';
}
printf("Please input target status:/n");
scanf("%s",&temp);
int j=0;
for ( j=0; j<9 && temp[j]-'0'>=0 && temp[j]-'0'<=8; j++)
{
target[j]=temp[j]-'0';
}
system("cls");
if ( i==9&&j==9)
{
break;
}
}
}        /* ----- end of function init ----- */
void
open_insert (numNode *head,numNode *item)
{
numNode *p,*q;
p=head->next;
q=head;
while ( p!=NULL && item->value > p->value )
{
q=p;
p=p->next;
}
q->next=item;
item->pre=q;
item->next=p;
if(p!=NULL)
{
p->pre=item;
}
}        /* ----- end of function open_insert ----- */
numNode *
open_getfirst (numNode *head)
{
numNode *p;
if ( head->next == NULL )
{
return NULL;
}
p=head->next;
head->next=p->next;
if ( p->next != NULL )
{
p->next->pre=head;
}
p->pre=NULL;
p->next=NULL;
return p;
}        /* ----- end of function open_getfirst ----- */
void
close_append (numNode *head,numNode *item)
{
item->next=head->next;
item->pre=head;
head->next=item;
if ( item->next!=NULL )
{
item->next->pre=item;
}
}        /* ----- end of function close_append ----- */
int
expand (numNode *p1)
{
numNode * p2;
int op=1;
for ( op=1; op<=4; op++)
{
p2=copy_numNode(p1);
operate(p2->num,op);
if(isNewNode(open,close,p2->num)=='N')
{
p2->parent=p1;
p2->deepth=p1->deepth+1;
p2->diffnum=diff(p2->num);
p2->value=p2->deepth+p2->diffnum;
if(p2->diffnum==0)
{
total_step=print_result(p2);
printf("Total step: %d/n",total_step);
free_list(open);
free_list(close);
return 1;
}
else
{
numNode_num++;
open_insert(open,p2);
}
}
else
free(p2);
}
return 0;
}        /* ----- end of function expand ----- */
int
operate(int m[], int op)
{
int blank;
blank=0;
while (m[blank]!=0 && blank<9 )
++blank;
if (blank==9)
return 1;
switch (op) {
case 1: /* up */
if (blank>2)
swap(m+blank,m+blank-3);
break;
case 2: /* down */
if (blank<6)
swap(m+blank,m+blank+3);
break;
case 3: /* left */
if (blank!=0 && blank!=3 && blank!=6)
swap(m+blank,m+blank-1);
break;
case 4: /* right */
if (blank!=2 && blank!=5 && blank!=8)
swap(m+blank,m+blank+1);
break;
default : return 1;
}
return 0;
}
void
swap(int *a, int *b)
{
int c;
c=*a;
*a=*b;
*b=c;
}
numNode *
copy_numNode (numNode *origin)
{
numNode *p;
p=create_numNode();
p->deepth=origin->deepth;
p->diffnum=origin->diffnum;
p->value=origin->value;
int i;
for ( i=0; i<9; i++)
{
(p->num)[i]=(origin->num)[i];
}
return p;
}        /* ----- end of function copy_numNode ----- */
int
diff (int num[9])
{
int i,diffnum=0;
for(i=0;i<9;i++)
if(num[i]!=target[i])
diffnum++;
return diffnum;
}        /* ----- end of function diff ----- */
char
isNewNode (numNode *open,numNode *close,int num[9])
{
numNode *p;
int i=0;
p=open->next;
while ( p!=NULL )
{
for ( i=0; i<9; i++)
{
if(p->num[i]!=num[i])
break;
}
if(i==9)
return 'O'; //Open
p=p->next;
}
p=close->next;
while ( p!=NULL )
{
for ( i=0; i<9; i++)
{
if(p->num[i]!=num[i])
break;
}
if(i==9)
return 'C'; //Close
p=p->next;
}
return 'N';
}        /* ----- end of function isNewNode ----- */
void
free_list (numNode *head)
{
numNode *p,*q;
p=head->next;
while ( p!=NULL )
{
q=p->next;
free(p);
p=q;
}
free(head);
}        /* ----- end of function free_list ----- */
void
print_num (int num[9])
{
int i;
for ( i=0; i<9; i++)
{
printf("%d/t",num[i]);
if((i%3)==2)
printf("/n");
}
}        /* ----- end of function print_num ----- */
int
print_result ( numNode *item)
{
numNode *p;
int step;
p=item;
if(p!=NULL)
{
step=print_result(p->parent);
printf("/nStep %d:/n",step+1);
print_num(p->num);
return step+1;
}
else
{
return -1;
}
}        /* ----- end of function print_result ----- */