Cleaning Robot POJ - 2688

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstring>
  4 #include <algorithm>
  5 #include <queue>
  6 #include <map>
  7 #include <cmath>
  8 #include <iomanip>
  9 using namespace std;
 10 
 11 typedef long long LL;
 12 #define inf (1LL << 25)
 13 #define rep(i,j,k) for(int i = (j); i <= (k); i++)
 14 #define rep__(i,j,k) for(int i = (j); i < (k); i++)
 15 #define per(i,j,k) for(int i = (j); i >= (k); i--)
 16 #define per__(i,j,k) for(int i = (j); i > (k); i--)
 17 
 18 const int N = 30;
 19 int mv_x[] = {0,0,1,-1};
 20 int mv_y[] = {1,-1,0,0};
 21 char mp[N][N];
 22 int sign[N][N];
 23 bool vis[N][N];
 24 bool vvv[N];
 25 int head[N];
 26 int cnt;//链式前向星
 27 int go;
 28 int num;
 29 int ans;
 30 int n,m;
 31 
 32 struct Edge{
 33 
 34     int to;
 35     int w;
 36     int next;
 37 
 38 }edge[1000];
 39 
 40 struct node{
 41     int x,y,cost;
 42     node(){}
 43     node(int a,int b,int c){
 44         x = a;
 45         y = b;
 46         cost = c;
 47     }
 48 };
 49 
 50 void add(int u,int v,int w){
 51     
 52     edge[cnt].to = v;
 53     edge[cnt].w = w;
 54     edge[cnt].next = head[u];
 55     head[u] = cnt++;
 56 }
 57 
 58 inline bool check(int x,int y){
 59     return x >= 1 && x <= n && y >= 1 && y <= m;
 60 }
 61 
 62 void bfs(int x,int y,int u){
 63 
 64     rep(i,1,n) rep(j,1,m) vis[i][j] = false;
 65 
 66     queue<node > que;
 67     que.push(node{ x, y, 0 });
 68     vis[x][y] = true;
 69 
 70     while(!que.empty()){
 71     
 72         node tmp = que.front();
 73         que.pop();
 74 
 75         rep__(p,0,4){
 76             int dx = tmp.x + mv_x[p];
 77             int dy = tmp.y + mv_y[p];
 78 
 79             if(check(dx,dy) && !vis[dx][dy] && mp[dx][dy] != ‘x‘){
 80 
 81                 vis[dx][dy] = true;
 82                 node in(dx, dy, tmp.cost + 1);
 83                 que.push(in);
 84                 if(sign[dx][dy] != 0){
 85                     int v = sign[dx][dy];
 86                     add(u,v,in.cost);
 87                 }
 88             }
 89         }
 90     }
 91 
 92 }
 93 
 94 void dfs(int now,int W,int cnt){
 95 
 96     if(W > ans) return; //剪支
 97     if(cnt == num){
 98         ans = min(ans, W);
 99     }
100     else{
101 
102         for(int o = head[now]; ~o; o = edge[o].next){
103             int v = edge[o].to;
104             int w = edge[o].w;
105 
106             if(vvv[v]) continue;
107 
108             vvv[v] = true;
109             dfs(v,W + w,cnt + 1);
110             vvv[v] = false;
111         }
112     }
113 }
114 
115 int main(){
116 
117     ios::sync_with_stdio(false);
118     cin.tie(0);
119 
120     while(cin >> m >> n){
121         if(n == 0 && m == 0) break;
122 
123         rep(i,1,n) rep(j,1,m) sign[i][j] = 0; //标记初始化
124         cnt = 0;//边数初始化
125         num = 0;//编号初始化
126         rep(i,1,N - 1) head[i] = -1; //头初始化
127 
128         rep(i,1,n) rep(j,1,m){
129             cin >> mp[i][j];
130             if(mp[i][j] == ‘o‘ || mp[i][j] == ‘*‘) sign[i][j] = ++num; //编号
131             if(mp[i][j] == ‘o‘) go = sign[i][j]; //起始点
132         }
133 
134         rep(i,1,n) rep(j,1,m){
135             if(sign[i][j] != 0) bfs(i,j,sign[i][j]);
136         }
137 
138         // rep__(i,1,N){
139         //     if(head[i] != -1){
140         //         cout << i << "--->:" << endl;
141 
142         //         for(int o = head[i]; ~o ; o = edge[o].next){
143         //             cout << edge[o].to << "  " << edge[o].w << endl;
144         //         }
145         //     }
146         // }
147 
148         vvv[go] = true;
149         ans = inf;
150         dfs(go,0,1);
151         vvv[go] = false;
152 
153         if(ans == inf) cout  << -1 << endl;
154         else cout << ans << endl;
155     }
156 
157     getchar(); getchar();
158     return 0;
159 }