sample.cpp

A*算法是

// sample.cpp : Defines the class behaviors for the application.
//

#include "stdafx.h"
#include "sample.h"
#include "sampleDlg.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif



            // #define NDEBUG
            #include <stdio.h>
            #include <conio.h>
            #include <assert.h>
            #include <stdlib.h>
            #define MAPMAXSIZE 100  //地图面积最大为 100x100
            #define MAXINT 8192     //定义一个最大整数, 地图上任意两点距离不会超过它
            #define STACKSIZE 65536 //保存搜索节点的堆栈大小
            #define tile_num(x,y) ((y)*map_w+(x))  //将 x,y 坐标转换为地图上块的编号
            #define tile_x(n) ((n)%map_w)          //由块编号得出 x,y 坐标
            #define tile_y(n) ((n)/map_w)
            // 树结构, 比较特殊, 是从叶节点向根节点反向链接
 
/////////////////////////////////////////////////////////////////////////////
// CSampleApp

BEGIN_MESSAGE_MAP(CSampleApp, CWinApp)
	//{{AFX_MSG_MAP(CSampleApp)
		// NOTE - the ClassWizard will add and remove mapping macros here.
		//    DO NOT EDIT what you see in these blocks of generated code!
	//}}AFX_MSG
	ON_COMMAND(ID_HELP, CWinApp::OnHelp)
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CSampleApp construction

CSampleApp::CSampleApp()
{
	// TODO: add construction code here,
	// Place all significant initialization in InitInstance
}

/////////////////////////////////////////////////////////////////////////////
// The one and only CSampleApp object

CSampleApp theApp;

/////////////////////////////////////////////////////////////////////////////
// CSampleApp initialization

BOOL CSampleApp::InitInstance()
{
	AfxEnableControlContainer();

	// Standard initialization
	// If you are not using these features and wish to reduce the size
	//  of your final executable, you should remove from the following
	//  the specific initialization routines you do not need.

#ifdef _AFXDLL
	Enable3dControls();			// Call this when using MFC in a shared DLL
#else
	Enable3dControlsStatic();	// Call this when linking to MFC statically
#endif

	CSampleDlg dlg;
	m_pMainWnd = &dlg;
	int nResponse = dlg.DoModal();
	if (nResponse == IDOK)
	{
		// TODO: Place code here to handle when the dialog is
		//  dismissed with OK
	}
	else if (nResponse == IDCANCEL)
	{
		// TODO: Place code here to handle when the dialog is
		//  dismissed with Cancel
	}

	// Since the dialog has been closed, return FALSE so that we exit the
	//  application, rather than start the application's message pump.
	return FALSE;
}
 












LINK queue;               // 保存没有处理的行走方法的节点
TREE stack[STACKSIZE];    // 保存已经处理过的节点 (搜索完后释放)
int stacktop;
unsigned char map[MAPMAXSIZE][MAPMAXSIZE];   //地图数据
int dis_map[MAPMAXSIZE][MAPMAXSIZE];         //保存搜索路径时,中间目标地最优解
int map_w,map_h;                             //地图宽和高
int start_x,start_y,end_x,end_y;             //地点,终点坐标
// 初始化队列


void init_queue()
{
	 queue=(LINK)malloc(sizeof(*queue));
	 queue->node=NULL;
	 queue->f=-1;
	 queue->next=(LINK)malloc(sizeof(*queue));
	 queue->next->f=MAXINT;
	 queue->next->node=NULL;
	 queue->next->next=NULL;
}
// 待处理节点入队列, 依靠对目的地估价距离插入排序
void enter_queue(TREE node,int f)
{
	 LINK p=queue,father,q;
	 while(f>p->f) {
	   father=p;
	   p=p->next;
	   assert(p);
	   }
	 q=(LINK)malloc(sizeof(*q));
	 assert(queue);
	 q->f=f,q->node=node,q->next=p;
	 father->next=q;
}
// 将离目的地估计最近的方案出队列
TREE get_from_queue()
{
	 TREE bestchoice=queue->next->node;
	 LINK next=queue->next->next;
	 free(queue->next);
	 queue->next=next;
	 stack[stacktop++]=bestchoice;
	 assert(stacktop<STACKSIZE);
	 return bestchoice;
}
// 释放栈顶节点
void pop_stack()
{
	 free(stack[--stacktop]);
}
// 释放申请过的所有节点
void freetree()
{
	 int i;
	 LINK p;
	 for (i=0;i<stacktop;i++)
		free(stack[i]);
	 while (queue) {
	   p=queue;
	   free(p->node);
	   queue=queue->next;
	   free(p);
	   }
}
// 估价函数,估价 x,y 到目的地的距离,估计值必须保证比实际值小
int judge(int x,int y)
{
	 int distance;
	 distance=abs(end_x-x)+abs(end_y-y);
	 return distance;
}
// 尝试下一步移动到 x,y 可行否
int trytile(int x,int y,TREE father)
{
	 TREE p=father;
	 int h;
	 if (map[y][x]!=' ') return 1; // 如果 (x,y) 处是障碍,失败
	 while (p) {
	   if (x==tile_x(p->tile) && y==tile_y(p->tile)) return 1; //如果 (x,y) 曾经经过,失败 

	   p=p->father;
	   }
	 h=father->h+1;
	 if (h>=dis_map[y][x]) return 1; // 如果曾经有更好的方案移动到 (x,y) 失败
	 dis_map[y][x]=h; // 记录这次到 (x,y) 的距离为历史最佳距离
	// 将这步方案记入待处理队列
	 p=(TREE)malloc(sizeof(*p));
	 p->father=father;
	 p->h=father->h+1;
	 p->tile=tile_num(x,y);
	 enter_queue(p,p->h+judge(x,y));
	 return 0;
}
            // 路径寻找主函数
void findpath(int *path)
{
	 TREE root;
	 int i,j;
	 stacktop=0;
	 for (i=0;i<map_h;i++)
		 for (j=0;j<map_w;j++)
			 dis_map[i][j]=MAXINT;
	 init_queue();
	 root=(TREE)malloc(sizeof(*root));
	 root->tile=tile_num(start_x,start_y);
	 root->h=0;
	 root->father=NULL;
	 enter_queue(root,judge(start_x,start_y));
	for (;;)
	{
		int x,y,child;
		TREE p;
		root=get_from_queue();
		if (root==NULL) {
		  *path=-1;
		  return;
		}
		x=tile_x(root->tile);
		y=tile_y(root->tile);
		
		if (x==end_x && y==end_y) break; // 达到目的地成功返回
		
		child=trytile(x,y-1,root);  //尝试向上移动
		child&=trytile(x,y+1,root); //尝试向下移动
		child&=trytile(x-1,y,root); //尝试向左移动
		child&=trytile(x+1,y,root); //尝试向右移动
		
		if (child!=0)
		   pop_stack();  // 如果四个方向均不能移动,释放这个死节点
    }
// 回溯树，将求出的最佳路径保存在 path[] 中
	 for (i=0;root;i++)
	 {
		path[i]=root->tile;
		root=root->father;
	 }
	 path[i]=-1;
	 freetree();
}
void printpath(int *path)
{
 int i;
 for (i=0;path[i]>=0;i++) {
    gotoxy(tile_x(path[i])+1,tile_y(path[i])+1);
    cprintf(\xfe);
    }
}
int readmap()
{
	 FILE *f;
	 int i,j;
	 f=fopen(map.dat,r);

	 assert(f);

	 fscanf(f,%d,%d\n,&map_w,&map_h);
	 for (i=0;i<map_h;i++)
	 fgets(&map[i][0],map_w+1,f);
	 fclose(f);
	 start_x=-1,end_x=-1;
	 for (i=0;i<map_h;i++)
		 for (j=0;j<map_w;j++) {
			 if (map[i][j]=='s') map[i][j]=' ',start_x=j,start_y=i;
			 if (map[i][j]=='e') map[i][j]=' ',end_x=j,end_y=i;
			 }
	 assert(start_x>=0 && end_x>=0);
	 return 0;
}
void showmap()
{
	int i,j;
	clrscr();
	for (i=0;i<map_h;i++)
	{
		gotoxy(1,i+1);
		for (j=0;j<map_w;j++)
			if (map[i][j]!=' ') cprintf(\xdb);
			else cprintf( );
    }
	gotoxy(start_x+1,start_y+1);
	 cprintf(s);
	 gotoxy(end_x+1,end_y+1);
	 cprintf(e);
}
/*int main()
{
 int path[MAXINT];
 readmap();
 showmap();
 getch();
 findpath(path);
 printpath(path);
 getch();
 return 0;
}*/