J - Borg Maze
思路：bfs+最小生成树。
#include<queue> #include<cstdio> #include<cstring> #include<iostream> #include<algorithm> #define MAXN 110 using namespace std; int fa[MAXN]; struct nond{int x,y,z; }v[MAXN*MAXN]; struct none{int x,y,z; }; int dx[4]={1,-1,0,0}; int dy[4]={0,0,1,-1}; int t,n,m,tot,sum,ans,point; int map[MAXN][MAXN],vis[MAXN][MAXN]; void bfs(int x,int y){queue<none>que;none s;s.x=x;s.y=y;s.z=0;memset(vis,0,sizeof(vis));vis[x][y]=1;que.push(s);int k=1;while(!que.empty()){none now=que.front();que.pop();for(int i=0;i<4;i++){int cx=now.x+dx[i];int cy=now.y+dy[i];int cz=now.z+1;if(cx>=1&&cx<=n&&cy>=1&&cy<=m&&map[cx][cy]>=0&&!vis[cx][cy]){if(map[cx][cy]>0){ v[++tot].x=map[x][y];v[tot].y=map[cx][cy];v[tot].z=cz;k++; }if(k==point) return ;none tmm;tmm.x=cx;tmm.y=cy;tmm.z=cz;vis[cx][cy]=1;que.push(tmm);}}} } int cmp(nond a,nond b){return a.z<b.z; } int find(int x){if(fa[x]==x) return x;else return fa[x]=find(fa[x]); } int main(){scanf("%d",&t);char tmp[MAXN];while(t--){scanf("%d%d",&m,&n);gets(tmp);for(int i=1;i<=n;i++){for(int j=1;j<=m;j++){char x;scanf("%c",&x);if(x=='#') map[i][j]=-1;else if(x==' ') map[i][j]=0;else map[i][j]=++point;}char c;scanf("%c",&c);}for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)if(map[i][j]>0) bfs(i,j);sort(v+1,v+1+tot,cmp);for(int i=1;i<=point;i++) fa[i]=i;for(int i=1;i<=tot;i++){int dx=find(v[i].x);int dy=find(v[i].y);if(dx==dy) continue;fa[dy]=dx;sum++;ans+=v[i].z;if(sum==point-1) break;}cout<<ans<<endl;ans=0;tot=0;sum=0;point=0;} }
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