p1199八数码问题

Posted 2020-08-21 CHADLZX

oj上简化的八数码问题，最强的数据仅仅是20步；

根据曼哈顿距离构造启发函数；

主算法：IDA*；(使用方法好像不太对......)

未用位运算优化；

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<string>
 6 #include<ctime>
 7 #include<cmath>
 8 #include<set>
 9 #include<map>
10 #include<queue>
11 #include<algorithm>
12 #include<iomanip>
13 #include<queue>
14 using namespace std;
15 #define FILE "dealing"
16 #define up(i,j,n) for(int i=(j);i<=(n);i++)
17 #define pii pair<int,int>
18 #define LL long long
19 namespace IO{
20     char buf[1<<15],*fs,*ft;
21     int gc(){return (fs==ft&&(ft=(fs=buf)+fread(buf,1,1<<15,stdin),fs==ft))?-1:*fs++;}
22     int read(){
23         int ch=gc(),f=0,x=0;
24         while(ch<\'0\'||ch>\'9\'){if(ch==\'-\')f=1;ch=gc();}
25         while(ch>=\'0\'&&ch<=\'9\'){x=(x<<1)+(x<<3)+ch-\'0\';ch=gc();}
26         return f?-x:x;
27     }
28 }using namespace IO;
29 const int maxn=10;
30 char ch[maxn],en[maxn]={\'1\',\'2\',\'3\',\'8\',\'0\',\'4\',\'7\',\'6\',\'5\'};
31 int a[3][3];
32 int p[10][10]={
33 {0,1,2,1,2,3,2,3,4},
34 {1,0,1,2,1,2,3,2,3},
35 {2,1,0,3,2,1,4,3,2},
36 {1,2,3,0,1,2,1,2,3},
37 {2,1,2,1,0,1,2,1,2},
38 {3,2,1,2,1,0,3,2,1},
39 {2,3,4,1,2,3,0,1,2},
40 {3,2,3,2,1,2,1,0,1},
41 {4,3,2,3,2,1,2,1,0}
42 };
43 int x[10],y[10];
44 inline int check(int a[][3]){
45     int ans=0;
46     up(i,1,3)x[a[0][i-1]]=i-1;
47     up(i,4,6)x[a[1][i-4]]=i-1;
48     up(i,7,9)x[a[2][i-7]]=i-1;
49     up(i,0,8)ans+=p[x[i]][y[i]];
50     return ans;
51 }
52 const int dx[4]={0,0,1,-1},dy[4]={1,-1,0,0};
53 bool flag=0;
54 int ans=10000;
55 int MaxH=0;
56 void dfs(int a[][3],int d){
57     int xx,yy;
58     xx=check(a);
59     if(!xx){flag=1;ans=min(ans,d);return;}
60     if(d+xx>MaxH)return;
61     up(i,0,2)up(j,0,2){
62         if(a[i][j])continue;
63         up(k,0,3){
64             xx=i+dx[k],yy=j+dy[k];
65             if(xx<0||yy<0||xx>2||yy>2)continue;
66             swap(a[xx][yy],a[i][j]);
67             dfs(a,d+1);
68             swap(a[xx][yy],a[i][j]);
69         }
70     }
71     return;
72 }
73 int main(){
74     freopen(FILE".in","r",stdin);
75     freopen(FILE".out","w",stdout);
76     scanf("%s",ch);
77     up(i,0,8)y[en[i]-\'0\']=i;
78     up(i,1,3)a[0][i-1]=ch[i-1]-\'0\';up(i,4,6)a[1][i-4]=ch[i-1]-\'0\';up(i,7,9)a[2][i-7]=ch[i-1]-\'0\';
79     for(int i=2;;i+=2){
80         MaxH=i;
81         dfs(a,0);
82         if(flag)break;
83     }
84     printf("%d\\n",ans);
85     cout<<"The time has passed "<<clock()<<" ms."<<endl;
86     return 0;
87 }

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