Hdu 4771 calculates a point to traverse all the shortest paths to the specified point (bfs + dfs), hdubfs

Hdu 4771 calculates a point to traverse all the shortest paths to the specified point (bfs + dfs), hdubfs

The question is as follows. The problem is as follows.

Because there are at most four targets, bfs has two short circuits (including the Starting Point) first, and dfs has a short circuit .) 0s1A)

#include<iostream>#include<vector>#include<cstdio>#include<cstring>#include<queue>using namespace std;struct point{    int x,y;    int cnt;};char a[105][105];vector<point>po;int n,m;int k;int mindis[10][10];int vis[105][105];int f[4][2]={0,1,0,-1,1,0,-1,0};int bfs(int s,int t){      memset(vis,0,sizeof(vis));      queue<point>q;      po[s].cnt=0;      po[t].cnt=-1;      q.push(po[s]);      vis[po[s].x][po[s].y]=1;      while(!q.empty())      {          point cur=q.front();          q.pop();          point next;          for(int i=0;i<4;i++)           {               next.x=cur.x+f[i][0];               next.y=cur.y+f[i][1];               if(next.x>=0&&next.x<n&&next.y>=0&&next.y<m&&vis[next.x][next.y]==0&&a[next.x][next.y]!='#')               {                   next.cnt=cur.cnt+1;                   if(next.x==po[t].x&&next.y==po[t].y)                   {                       return next.cnt;                   }                   q.push(next);                   vis[next.x][next.y]=1;               }           }      }      return -1;}int mins=100000000;int vis2[10];void dfs(int u,int lev,int sumdis){    if(sumdis>=mins)return ;    if(lev==k)    {        if(sumdis<mins)          {              mins=sumdis;return ;          }    }    for(int i=1;i<=k;i++)    {        if(!vis2[i])        {            vis2[i]=1;            dfs(i,lev+1,sumdis+mindis[u][i]);            vis2[i]=0;        }    }}int main(){    while(~scanf("%d%d",&n,&m)&&(n||m))    {       memset(mindis,0,sizeof(mindis));       mins=100000000;        po.clear();        for(int i=0;i<n;i++)        {          getchar();           for(int j=0;j<m;j++)          {             scanf("%c",&a[i][j]);             if(a[i][j]=='@')              {                  point txy;txy.x=i;txy.y=j;                  po.push_back(txy);              }          }        }        scanf("%d",&k); int aa,bb;        for(int i=0;i<k;i++)          {              scanf("%d%d",&aa,&bb);              point txy;txy.x=aa-1;txy.y=bb-1;              po.push_back(txy);          }        int mark=1;       for(int i=0;i<k+1;i++)        for(int j=i+1;j<k+1;j++)           {               mindis[j][i]=mindis[i][j]=bfs(i,j);               if(mindis[i][j]==-1)                {                   mark=0;break;                }           }        if(mark==0)        {            printf("-1\n");continue;        }       memset(vis2,0,sizeof(vis2));       dfs(0,0,0);       printf("%d\n",mins);    }}