UVa-1604 Cubic Eight-Puzzle

  1 #include <bits/stdc++.h>
  2 #define _for(i,a,b) for(int i = (a);i < (b);i ++)
  3 using namespace std;
  4 struct cell
  5 {
  6     int t;
  7     int f;
  8 };
  9 
 10 typedef cell State[9];
 11 const int maxstate = 1000000;
 12 State st[maxstate],goal;
 13 int dist[maxstate];
 14 
 15 const int dx[] = {-1,1,0,0};
 16 const int dy[] = {0,-1};
 17 
 18 bool equ(State s)
 19 {
 20     _for(i,9)
 21         if(s[i].t != goal[i].t)    return false;
 22     return true;
 23 }
 24 
 25 bool limit(int x,int y)
 26 {
 27     return x>=0&&x<3&&y>=0&&y<3;
 28 }
 29 
 30 set<int> vis;
 31 void init_lookup_table() {vis.clear();}
 32 bool try_to_insert(int s)
 33 {
 34     int v = 0;
 35     _for(i,9)    
 36     {
 37         if(st[s][i].t<0)
 38             v = v*10+9;
 39         else
 40             v = v*10+(st[s][i].t*3)+st[s][i].f;
 41     }
 42     if(vis.count(v)) return false; 
 43     vis.insert(v);
 44     return true;
 45 }
 46 
 47 int bfs()
 48 {
 49     init_lookup_table();
 50     int front = 1,rear = 2;
 51     while(front<rear)
 52     {
 53         State& s = st[front];
 54         cout << dist[front] << endl;
 55         if(equ(s))    return front;
 56         int z;
 57         for(z = 0;z < 9;z ++) if(s[z].t<0) break;
 58         int x = z/3,y = z%3;
 59         _for(d,4)
 60         {
 61             int newx = x+dx[d];
 62             int newy = y+dy[d];
 63             int newz = newx*3+newy;
 64             if(limit(newx,newy))
 65             {
 66                 State& t = st[rear];
 67                 memcpy(&t,&s,sizeof(s));
 68                 if(newx==x)
 69                     t[z] = (cell){3-s[newz].t-s[newz].f,s[newz].f};
 70                 else if(newy==y)
 71                     t[z] = (cell){s[newz].f,s[newz].t};
 72                 t[newz] = (cell){-1,-1};
 73                 dist[rear] = dist[front]+1;
 74                 if(try_to_insert(rear)) rear ++;
 75             }
 76         }
 77         front ++;
 78     }
 79     return -1;
 80 }
 81 
 82 int main()
 83 {
 84     int tx,ty;
 85     while(scanf("%d%d",&tx,&ty)==2&&tx!=0)
 86     {
 87         _for(i,9) st[1][i] = (cell){0,1};
 88         st[1][(ty-1)*3+tx-1] = (cell){-1,-1};
 89         _for(i,9)
 90         {
 91             char c;
 92             cin >> c;
 93             if(c==‘E‘)    goal[i].t = -1;
 94             else if(c==‘W‘) goal[i].t = 0;
 95             else if(c==‘R‘) goal[i].t = 1;
 96             else if(c==‘B‘) goal[i].t = 2;
 97         }
 98         int ans = bfs();
 99         if(ans>0)    printf("%dn",dist[ans]);
100         else printf("-1n");
101         return 0;
102     }
103     return 0;
104 }

  1 #include <bits/stdc++.h>
  2 #define _for(i,b) for(int i = (a);i < (b);i ++)
  3 using namespace std;
  4 struct cell
  5 {
  6     int t;
  7     int f;
  8 };
  9 
 10 struct State
 11 {
 12     cell c[9];
 13     int d;
 14 };
 15 
 16 const int maxstate = 1000000;
 17 State st,goal;
 18 int dist[maxstate];
 19 
 20 const int dx[] = {-1,0};
 21 const int dy[] = {0,-1};
 22 
 23 int diff(State s)
 24 {
 25     int cnt = 0;
 26     _for(i,9)
 27     {
 28         if(s.c[i].t != goal.c[i].t) cnt ++;
 29     }
 30     return cnt;
 31 }
 32 
 33 bool limit(int x,int y)
 34 {
 35     return x>=0&&x<3&&y>=0&&y<3;
 36 }
 37 
 38 set<int> vis;
 39 void init_lookup_table()
 40 {
 41     vis.clear();
 42 }
 43 bool try_to_insert(State s)
 44 {
 45     int v = 0;
 46     _for(i,9)
 47     {
 48         if(s.c[i].t<0)
 49             v = v*10+9;
 50         else
 51             v = v*10+(s.c[i].t*3)+s.c[i].f;
 52     }
 53     if(vis.count(v)) return false;
 54     vis.insert(v);
 55     return true;
 56 }
 57 
 58 struct cmp
 59 {
 60     bool operator () (State a,State b)
 61     {
 62         if(a.d==b.d)
 63         {
 64             int aa = diff(a);
 65             int bb = diff(b);
 66             return aa>bb;
 67         }
 68         else
 69             return a.d>b.d;
 70     }
 71 };
 72 
 73 int bfs()
 74 {
 75     init_lookup_table();
 76     priority_queue<State,vector<State>,cmp> q;
 77     st.d = 0;
 78     q.push(st);
 79     while(!q.empty())
 80     {
 81         State s = q.top();
 82         q.pop();
 83         if(diff(s)+s.d>31) continue;
 84         if(!diff(s)) return s.d;
 85         int z;
 86         for(z = 0; z < 9; z ++) if(s.c[z].t<0) break;
 87         int x = z/3,y = z%3;
 88         _for(d,4)
 89         {
 90             int newx = x+dx[d];
 91             int newy = y+dy[d];
 92             int newz = newx*3+newy;
 93             if(limit(newx,newy))
 94             {
 95                 State t;
 96                 memcpy(&t,sizeof(s));
 97                 if(newx==x)
 98                     t.c[z] = (cell)
 99                 {
100                     3-s.c[newz].t-s.c[newz].f,s.c[newz].f
101                 };
102                 else if(newy==y)
103                     t.c[z] = (cell)
104                 {
105                     s.c[newz].f,s.c[newz].t
106                 };
107                 t.c[newz] = (cell)
108                 {
109                     -1,-1
110                 };
111                 t.d = s.d+1;
112                 if(try_to_insert(t)) q.push(t);
113             }
114         }
115     }
116     return -1;
117 }
118 
119 int main()
120 {
121     int tx,ty;
122     while(scanf("%d%d",&ty)==2&&tx!=0)
123     {
124         _for(i,9) st.c[i] = (cell)
125         {
126             0,1
127         };
128         st.c[(ty-1)*3+tx-1] = (cell)
129         {
130             -1,-1
131         };
132         _for(i,9)
133         {
134             char c;
135             cin >> c;
136             if(c==‘E‘)    goal.c[i].t = -1;
137             else if(c==‘W‘) goal.c[i].t = 0;
138             else if(c==‘R‘) goal.c[i].t = 1;
139             else if(c==‘B‘) goal.c[i].t = 2;
140         }
141         int ans = bfs();
142         if(ans>=0)    printf("%dn",ans);
143         else printf("-1n");
144         return 0;
145     }
146     return 0;
147 }