POJ 1077 Eight A*

/*终于用A*做出了这道经典八数码*/
#include<stdio.h>
#include<cstring>
#include<cmath>
#include<string>
#include<queue>
using namespace std;
struct point{
	char board[10];
	int space;
};
int f[400000],d[400000];
int colour[400000],parent[400000],moves[400000],path[400000];
int fac[10]={ 1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880 };
int xx[4]={1,-1,0,0};
int yy[4]={0,0,1,-1};
struct cmp{    
	bool operator()(const int u,const int v){ 
		return f[u]>f[v];    
	}
};
int calhash(char * tmp){
	int i,j;
	int temp=0,sum=0;
	for(i=0;i<9;i++){
		temp=0;
		for(j=i+1;j<9;j++){
			if(tmp[i]>tmp[j])
				temp++;
		}
		sum+=temp*fac[9-i-1];
	}
	return sum;
}

int h(struct point & temp){
	int i,j,k,sum=0;
	for(i=0;i<3;i++)
		for(j=0;j<3;j++){
			k=i*3+j;
			if(temp.board[k]!='9'){
				sum+=abs(i-(temp.board[k]-'1')/3)+abs(j-(temp.board[k]-'1')%3);
			}
		}
	return sum;
}

void get_node(int per,struct point & cur){
	int i,j=0,k,temp,flag[10];
	memset(flag,0,sizeof(flag));
	for(i=8;i>=0;i--){
		temp=0;
		cur.board[j]=per/fac[i];
		for(k=1;k<10;k++){
			if(temp==cur.board[j] && flag[k]==0)
				break;
			if(flag[k]==0)
				temp++;
		}
		flag[k]=1;
		cur.board[j]=k+'0';
		if(cur.board[j]=='9'){
			cur.space=j;
		}
		j++;
		per%=fac[i];
	}

}

int Astar(struct point & sta){
	int u,v,k,x,y,i,xxx,yyy,z;
	priority_queue<int,vector<int>,cmp> que;
	struct point cur,temp;
	moves[0]=-1;
	
	u=calhash(sta.board);
	f[u]=h(sta);
	d[u]=0;
	que.push(u);
	colour[u]=1;
	parent[u]=-1;
	while(!que.empty()){
		int tem;
		tem=que.top();
		if(tem==0)
			return 1;
		que.pop();

		get_node(tem,cur);

		k=cur.space;
		x=k/3;
		y=k%3;
		for(i=0;i<4;i++){
			xxx=x+xx[i];
			yyy=y+yy[i];
			if(xxx<0 || xxx>2 || yyy<0 || yyy>2)
				continue;
			temp.space=3*xxx+yyy;
			temp.board[temp.space]='9';
			temp.board[cur.space]=cur.board[temp.space];
			for(z=0;z<9;z++){
				if(z!= temp.space && z!=cur.space)
					temp.board[z]=cur.board[z];
			}
			v=calhash(temp.board);
			if(colour[v]==1 && (d[tem]+1<d[v])){
				moves[v]=i;
				parent[v]=tem;
				f[v]=f[v]-d[v]+d[tem]+1;
				d[v]=d[tem]+1;
			}
			else if(colour[v]==2 && (d[tem]+1<d[v])){
				moves[v]=i;
				parent[v]=tem;
				f[v]=f[v]-d[v]+d[tem]+1;
				d[v]=d[tem]+1;
				colour[v]=1;
				que.push(v);
			}
			else if(colour[v]==0){
				moves[v]=i;
				parent[v]=tem;
				d[v]=d[tem]+1;
				f[v]=d[v]+h(temp);
				que.push(v);
				colour[v]=1;
			}
		}
		colour[tem]=2;
	}
	return 0;
}

void printpath(){
	int i,t;
	if(moves[0]==-1){
		printf("\n");
		return;
	}
	t=0;
	i=0;
	while(parent[t]!=-1){
		path[i++]=moves[t];
		t=parent[t];
	}
	--i;
	for(;i>=0;i--){
		if(path[i]==0)
			printf("d");
		else if(path[i]==1)
			printf("u");
		else if(path[i]==2)
			printf("r");
		else
			printf("l");
	}
	printf("\n");
}

int main(){
	int i,j,k;
	char input[30];
	gets(input);
		i=0;j=0;

		struct point sta;
		while(input[i]!='\0'){
			if(input[i]==' ')
				;
			else if(input[i]=='x'){
				sta.board[j++]='9';
				sta.space=j-1;
			}
			else
				sta.board[j++]=input[i];
			i++;
		}
		if(Astar(sta)){
			printpath();
		}
		else
			printf("unsolvable\n");
	
}