HDU 5025Saving Tang Monk BFS + 二进制枚举状态

  1 //#pragma comment(linker, "/STACK:16777216") //for c++ Compiler
  2 #include <stdio.h>
  3 #include <iostream>
  4 #include <cstring>
  5 #include <cmath>
  6 #include <stack>
  7 #include <queue>
  8 #include <vector>
  9 #include <algorithm>
 10 #define ll long long
 11 #define Max(a,b) (((a) > (b)) ? (a) : (b))
 12 #define Min(a,b) (((a) < (b)) ? (a) : (b))
 13 #define Abs(x) (((x) > 0) ? (x) : (-(x)))
 14 using namespace std;
 15 
 16 const int INF = 0x3f3f3f3f;
 17 const int MAXN = 220;
 18 const double eps = 1e-9;
 19 
 20 struct node{
 21     int x,y,step;
 22 };
 23 
 24 char map[105][105];
 25 int vis[105][105];
 26 int to[4][2]= {1,0,-1,0,0,1,0,-1};
 27 int n,m,sx,sy,ex,ey,ans;
 28 
 29 bool operator < (node a, node b){
 30     return a.step > b.step;
 31 }
 32 
 33 int check(int x,int y){
 34     if(x<0 || x>=n || y<0 || y>=n)
 35         return 1;
 36     if(map[x][y]==‘#‘ || vis[x][y])
 37         return 1;
 38     return 0;
 39 }
 40 
 41 void bfs(int sx, int sy, int k){
 42     int i;
 43     priority_queue <node> Q;
 44     node a,next;
 45     a.x = sx;
 46     a.y = sy;
 47     a.step = 0;
 48     vis[a.x][a.y]=1;
 49     Q.push(a);
 50     while(!Q.empty()){
 51         a = Q.top();
 52         //printf("x = %d y = %d step = %d\n",a.x,a.y,a.step);
 53         Q.pop();
 54         if(k <= m){
 55             if(map[a.x][a.y] == k + ‘0‘){
 56                 ans += a.step;
 57                 ex = a.x;
 58                 ey = a.y;
 59                 //printf("%d %d cur _ ans = %d\n",ex, ey,ans);
 60                 return;
 61             }
 62         } else{
 63             if(map[a.x][a.y] == ‘T‘){
 64                 ans += a.step;
 65                 ex = a.x;
 66                 ey = a.y;
 67                 //printf("%d %d cur _ ans = %d\n",ex, ey,ans);
 68                 return;
 69             }
 70         }
 71         for(i = 0; i<4; i++){
 72             next = a;
 73             next.x+=to[i][0];
 74             next.y+=to[i][1];
 75             if(check(next.x,next.y))    continue;
 76             next.step=a.step+1;
 77             if(map[a.x][a.y] == ‘S‘){
 78                 ++next.step;
 79             }
 80             vis[next.x][next.y] = 1;
 81             Q.push(next);
 82         }
 83         if(map[a.x][a.y] == ‘S‘){
 84             map[a.x][a.y] = ‘.‘;
 85         }
 86     }
 87     ans =INF;
 88     return ;
 89 }
 90 
 91 void dfs(int x, int y){
 92     for(int i = 0; i<4; i++){
 93             int _x = x + to[i][0];
 94             int _y = y + to[i][1];
 95             if(check(_x,_y))  continue;
 96             if(map[_x][_y] != ‘#‘){
 97                 vis[_x][_y] = 1;
 98                 dfs(_x,_y);
 99             }
100     }
101 }
102 int main(){
103     int i,j,cc,s_flag;
104     while(EOF != scanf("%d%d",&n,&m)){
105         if(n == 0 && m == 0)    break;
106         s_flag = 0;
107         node S[6];
108         for(i = 0; i<n; i++)
109             scanf("%s",map[i]);
110         for(i = 0; i<n; i++){
111             for(j = 0; j<n; j++){
112                 if(map[i][j]==‘K‘){
113                     sx = i;
114                     sy = j;
115                 }else if(map[i][j] == ‘T‘){
116                     ex = i,ey = j;
117                 }else if(map[i][j] == ‘S‘){
118                     S[s_flag].x = i, S[s_flag++].y = j;
119                 }
120             }
121         }
122         memset(vis,0,sizeof(vis));
123         vis[sx][sy] = 1;
124         dfs(sx,sy);
125         int kkk[11];
126         bool flag = false;
127         memset(kkk, 0, sizeof(kkk));
128         for(i = 0; i < n; ++i){
129             for(j = 0; j < n; ++j){
130                 if(map[i][j] >= ‘1‘ && map[i][j] <= ‘9‘ && vis[i][j]){
131                     kkk[map[i][j] - ‘0‘] = 1;
132                 }
133             }
134         }
135         for(i = 1; i <= m; ++i){
136             if(!kkk[i]) break;
137         }
138         if(i == m + 1)  flag = true;
139 
140         if(vis[ex][ey] == 0 || !flag){
141              printf("impossible\n");
142              continue;
143         }
144         s_flag = 0;
145         for(i = 0; i<n; i++){
146                 for(j = 0; j<n; j++){
147                     if(map[i][j] == ‘S‘){
148                         S[s_flag].x = i, S[s_flag++].y = j;
149                     }
150                 }
151         }
152         int minans=INF;
153         for(cc = 0; cc < (1 << s_flag); ++cc){
154             ans = 0;
155             for(i = 0; i <s_flag; ++i){
156                 if((1 << i) & cc){
157                     map[S[i].x][S[i].y] = ‘.‘;
158                     ans++;
159                 }
160                 else {
161                     map[S[i].x][S[i].y] = ‘#‘;
162                 }
163             }
164             for(i = 0; i < n; ++i){
165                 for(j = 0; j < n; ++j){
166                     if(map[i][j] == ‘K‘){
167                         ex = i;
168                         ey = j;
169                     }
170                 }
171             }
172             for(int k = 1; k <= m + 1; ++k){
173                 memset(vis, 0, sizeof(vis));
174                 sx = ex;
175                 sy = ey;
176                 bfs(sx, sy, k);
177             }
178             minans=min(minans,ans);
179         }
180         printf("%d\n",minans);
181     }
182     return 0;
183 }