AcWing 175. 电路维修

 1 #include <iostream>
 2 #include <cstring>
 3 #include <deque>
 4 using namespace std;
 5 const int N = 510;
 6 typedef pair<int,int> PII;
 7 char mp[N][N];
 8 int n,m,T,dist[N][N];
 9 char pre[] = {"\\//\\"};
10 int xx[4] = {1,1,-1,-1},yy[4] = {1,-1,1,-1};
11 bool st[N][N];
12 int bfs(int sx,int sy)
13 {
14     deque<PII> q;
15     q.push_back({sx,sy});
16     memset(dist,0x3f,sizeof dist);
17     memset(st,0,sizeof st);
18     dist[sx][sy] = 0;
19     while(q.size())
20     {
21         PII it = q.front();//实际是模拟了dijkstra算法.距离短的放前面,这样第一次到的点就是最短的点.
22         int x= it.first,y = it.second;
23         q.pop_front();
24         if(st[x][y]) continue;//已经用此点更新过就没必要再更新.
25         st[x][y] = 1;
26         for(int i=0;i<4;i++)
27         {
28             int dx = x+xx[i],dy = y+yy[i];
29             if(dx>0&&dx<=n+1&&dy>0&&dy<=m+1)
30             {
31                 char c = mp[min(dx,x)][min(dy,y)];
32                 int w = 1;
33                 if(c==pre[i]) w = 0;
34                 if(dist[dx][dy]>dist[x][y]+w)
35                 {
36                     dist[dx][dy] = dist[x][y]+w;
37                     if(!w) q.push_front({dx,dy});
38                     else q.push_back({dx,dy});
39                 }
40             }
41         }
42     }
43     return dist[n+1][m+1];
44 }
45 int main()
46 {
47     scanf("%d",&T);
48     while(T--)
49     {
50         scanf("%d%d",&n,&m);
51         for(int i=1;i<=n;i++) scanf("%s",mp[i]+1);
52         if(n+m&1) puts("NO SOLUTION");
53         else printf("%d\n",bfs(1,1));
54     }
55     return 0;
56 }