好像没啥可说的，就当练码力了......
先用BFS跑出岛屿，然后跑最短路求岛屿间的距离，最后状压DP得出答案
注意细节，码码码2333
1 #include<set> 2 #include<queue> 3 #include<cstdio> 4 #include<cstring> 5 #include<algorithm> 6 using namespace std; 7 const int N=16,M=256,L=55; 8 const int mov[4][2]={{0,1},{0,-1},{1,0},{-1,0}}; 9 struct a 10 { 11 int xx,yy; 12 }que[L*L]; 13 char mapp[L][L]; 14 int val[N][N],dp[1<<N][N]; 15 int Mapp[L][L],vis[L][L],dis[L][L]; 16 int n,m,f,b,nx,ny,land,shal,nde,all,ans=2e9; 17 deque<a> qs; 18 bool ok1(int x,int y) 19 { 20 return mapp[x][y]=='X'&&!Mapp[x][y]&&x>=1&&x<=n&&y>=1&&y<=m; 21 } 22 void BFS1(int x,int y) 23 { 24 que[f=b=0]=(a){x,y},Mapp[x][y]=++land; 25 while(f<=b) 26 { 27 a tn=que[f++]; 28 int tx=tn.xx,ty=tn.yy; 29 for(int i=0;i<4;i++) 30 if(ok1(nx=tx+mov[i][0],ny=ty+mov[i][1])) 31 Mapp[nx][ny]=land,que[++b]=(a){nx,ny}; 32 } 33 } 34 bool ok2(int x,int y) 35 { 36 return mapp[x][y]=='S'&&!Mapp[x][y]&&x>=1&&x<=n&&y>=1&&y<=m; 37 } 38 void BFS2(int x,int y) 39 { 40 que[f=b=0]=(a){x,y},Mapp[x][y]=--shal; 41 while(f<=b) 42 { 43 a tn=que[f++]; 44 int tx=tn.xx,ty=tn.yy; 45 for(int i=0;i<4;i++) 46 if(ok2(nx=tx+mov[i][0],ny=ty+mov[i][1])) 47 Mapp[nx][ny]=shal,que[++b]=(a){nx,ny}; 48 } 49 } 50 bool ok(int x,int y) 51 { 52 return Mapp[x][y]&&!vis[x][y]&&x>=1&&x<=n&&y>=1&&y<=m; 53 } 54 void BFS(int x,int y) 55 { 56 qs.push_back((a){x,y}); 57 memset(vis,0,sizeof vis); 58 memset(dis,0,sizeof dis); 59 nde=Mapp[x][y],val[nde][nde]=0,vis[x][y]=true; 60 while(!qs.empty()) 61 { 62 a tt=qs.front(); qs.pop_front(); int tx=tt.xx,ty=tt.yy; 63 for(int i=0;i<4;i++) 64 if(ok(nx=tx+mov[i][0],ny=ty+mov[i][1])) 65 { 66 vis[nx][ny]=true; 67 if(Mapp[tx][ty]<0) dis[nx][ny]=dis[tx][ty]+1,qs.push_back((a){nx,ny}); 68 else if(Mapp[tx][ty]>0) dis[nx][ny]=dis[tx][ty],qs.push_front((a){nx,ny}); 69 } 70 } 71 for(int i=1;i<=n;i++) 72 for(int j=1;j<=m;j++) 73 if(Mapp[i][j]>0) 74 val[nde][Mapp[i][j]]=min(val[nde][Mapp[i][j]],dis[i][j]); 75 } 76 int ins(int nde) 77 { 78 return 1<<(nde-1); 79 } 80 int main () 81 { 82 scanf("%d%d",&n,&m); 83 for(int i=1;i<=n;i++) 84 scanf("%s",mapp[i]+1); 85 for(int i=1;i<=n;i++) 86 for(int j=1;j<=m;j++) 87 if(ok1(i,j)) BFS1(i,j); 88 else if(ok2(i,j)) BFS2(i,j); 89 memset(val,0x3f,sizeof val); 90 for(int i=1;i<=n;i++) 91 for(int j=1;j<=m;j++) 92 if(Mapp[i][j]>0) BFS(i,j); 93 all=(1<<land)-1; 94 memset(dp,0x3f,sizeof dp); 95 for(int i=1;i<=land;i++) dp[ins(i)][i]=0; 96 for(int i=0;i<=all;i++) 97 for(int j=1;j<=land;j++) 98 if(i&ins(j)) 99 for(int k=1;k<=land;k++) 100 if(!(i&ins(k))&&j!=k) 101 dp[i|ins(k)][k]=min(dp[i|ins(k)][k],dp[i][j]+val[j][k]); 102 for(int i=1;i<=land;i++) ans=min(ans,dp[all][i]); 103 printf("%d",ans); 104 return 0; 105 }