硬核BFS，九维数组判重
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 struct State 10 { 11 cell c[9]; 12 int d; 13 }; 14 15 const int maxstate = 1000000; 16 State st,goal; 17 int dist[maxstate]; 18 19 const int dx[] = {-1,1,0,0}; 20 const int dy[] = {0,0,1,-1}; 21 22 int diff(State s) 23 { 24 int cnt = 0; 25 _for(i,0,9) 26 { 27 if(s.c[i].t != goal.c[i].t) cnt ++; 28 } 29 return cnt; 30 } 31 32 bool limit(int x,int y) 33 { 34 return x>=0&&x<3&&y>=0&&y<3; 35 } 36 37 int Hash[7][7][7][7][7][7][7][7][7]; 38 void init_lookup_table() 39 { 40 memset(Hash,0,sizeof(Hash)); 41 } 42 bool try_to_insert(State s) 43 { 44 int v = 0; 45 int index[9] {0}; 46 _for(i,0,9) 47 if(s.c[i].t==0&&s.c[i].f==1) 48 index[i] = 0; 49 else if(s.c[i].t==1&&s.c[i].f==0) 50 index[i] = 1; 51 else if(s.c[i].t==1&&s.c[i].f==2) 52 index[i] = 2; 53 else if(s.c[i].t==2&&s.c[i].f==1) 54 index[i] = 3; 55 else if(s.c[i].t==0&&s.c[i].f==2) 56 index[i] = 4; 57 else if(s.c[i].t==2&&s.c[i].f==0) 58 index[i] = 5; 59 else if(s.c[i].t<0) 60 index[i] = 6; 61 int &shash = Hash[index[0]][index[1]][index[2]][index[3]][index[4]][index[5]][index[6]][index[7]][index[8]]; 62 if(shash) 63 return false; 64 shash = 1; 65 return true; 66 } 67 68 int bfs() 69 { 70 init_lookup_table(); 71 queue<State> q; 72 st.d = 0; 73 q.push(st); 74 while(!q.empty()) 75 { 76 State s = q.front();q.pop(); 77 if(diff(s)+s.d>31) continue; 78 if(!diff(s)) return s.d; 79 int z; 80 for(z = 0; z < 9; z ++) if(s.c[z].t<0) break; 81 int x = z/3,y = z%3; 82 _for(d,0,4) 83 { 84 int newx = x+dx[d]; 85 int newy = y+dy[d]; 86 int newz = newx*3+newy; 87 if(limit(newx,newy)) 88 { 89 State t; 90 memcpy(&t,&s,sizeof(s)); 91 if(newx==x) 92 t.c[z] = (cell){3-s.c[newz].t-s.c[newz].f,s.c[newz].f}; 93 else if(newy==y) 94 t.c[z] = (cell){s.c[newz].f,s.c[newz].t}; 95 t.c[newz] = (cell){-1,-1}; 96 t.d = s.d+1; 97 if(try_to_insert(t)) q.push(t); 98 } 99 } 100 } 101 return -1; 102 } 103 104 int main() 105 { 106 int tx,ty; 107 while(scanf("%d%d",&tx,&ty)==2&&tx!=0) 108 { 109 _for(i,0,9) st.c[i] = (cell){0,1}; 110 st.c[(ty-1)*3+tx-1] = (cell){-1,-1}; 111 _for(i,0,9) 112 { 113 char c; 114 cin >> c; 115 if(c=='E') goal.c[i].t = -1; 116 else if(c=='W') goal.c[i].t = 0; 117 else if(c=='R') goal.c[i].t = 1; 118 else if(c=='B') goal.c[i].t = 2; 119 } 120 int ans = bfs(); 121 if(ans>=0) printf("%d ",ans); 122 else printf("-1 "); 123 } 124 return 0; 125 }