hdu 4414 Finding crosses

数据范围这么小，随便暴搜就可以过

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <vector>using namespace std;const int maxn=55;char mp[maxn][maxn];vector<pair<int,int> > g;bool vis[maxn][maxn];int dx[]={0,1,0,-1},n;int dy[]={1,0,-1,0};int Mx,My;void dfs(int x,int y){    if(x<Mx) Mx=x,My=y;    g.push_back(make_pair(x,y));    vis[x][y]=1;    for(int i=0;i<4;i++)    {        int nx=x+dx[i],ny=y+dy[i];        if(nx<0||nx>=n||ny<0||ny>=n||vis[nx][ny]||mp[nx][ny]!='#') continue;        dfs(nx,ny);    }}bool judge(int x,int y,int r){    if(!vis[x][y]) return 0;    int nx,ny;    for(int i=1;i<=r/2;i++)    {        nx=x,ny=y-i;        if(nx<0||nx>=n||ny<0||ny>=n||!vis[nx][ny]) return 0;    }    return 1;}int main(){    while(scanf("%d",&n)==1&&n)    {        int ans=0;        for(int i=0;i<n;i++) scanf("%s",mp[i]);        memset(vis,0,sizeof(vis));        for(int i=0;i<n;i++)        for(int j=0;j<n;j++)          if(!vis[i][j]&&mp[i][j]=='#')          {              Mx=100;              g.clear();              dfs(i,j);             // cout<<g.size()<<endl;              for(int r=3;r+r-1<=g.size();r+=2)                if(r+r-1==g.size())                {                   int x=Mx+r/2,y=My;                   if(judge(x,y,r)) ans++;                }          }        printf("%d\n",ans);    }    return 0;}