hdu5024-Wang Xifeng's Little Plot

此题一开始用暴力做，后来发现斜着走的时候其实暴力不太好写，于是改用搜索写了

 #include <iostream>
 #include <stdio.h>
 #include <memory.h>
 using namespace std;

 char a[][]= {};
 int down[][]= {};
 int up[][]= {};

 int cnt[][][]= {};
 int n;
 int dx[]= {-,,-, };
 int dy[]= {-,, ,-};
 int dfs(int curx,int cury,int num)
 {
     if(curx< || cury< || curx>=n || cury>=n)
         return ;
     int &ans=cnt[curx][cury][num];
     if(a[curx][cury]=='#')
         return ans=;
     return ans=+dfs(curx+dx[num],cury+dy[num],num);
 }

 int getMax()
 {
     int ans=;
     for(int i=; i<n; i++)
         for(int j=; j<n; j++)
         {
             ans=max(ans,down[i][j]+up[i][j]-);
         }
     return ans;
 }

 int main()
 {
     freopen("in.txt","r",stdin);

     while(scanf("%d",&n),n)
     {
         memset(down,,sizeof down);
         memset(up,,sizeof up);
         memset(cnt,,sizeof cnt);
         for(int i=; i<n; i++)
             scanf("%s",a[i]);

         for(int i=; i<n; i++)
             for(int j=; j<n; j++)
             {
                 if(a[i][j]=='#')
                 {
                     up[i][j]=down[i][j]=;

                 }
                 else
                 {
                     up[i][j]=down[i][j]=;
                     if(i!=)
                         up[i][j]=up[i-][j]+;
                     if(j!=)
                         down[i][j]=down[i][j-]+;
                 }
             }

         int ans=;
         ans=max(ans,getMax());

         memset(down,,sizeof down);
         memset(up,,sizeof up);
         for(int i=n-; i>=; i--)
             for(int j=n-; j>=; j--)
             {
                 if(a[i][j]=='#')
                 {
                     up[i][j]=down[i][j]=;
                 }
                 else
                 {
                     up[i][j]=down[i][j]=;
                     if(i!=n-)
                         up[i][j]=up[i+][j]+;
                     if(j!=n-)
                         down[i][j]=down[i][j+]+;
                 }
             }

         ans=max(ans,getMax());

 //---------------------------
         memset(down,,sizeof down);
         memset(up,,sizeof up);
         for(int i=; i<n; i++)
             for(int j=n-; j>=; j--)
             {
                 if(a[i][j]=='#')
                 {
                     up[i][j]=down[i][j]=;
                 }
                 else
                 {
                     up[i][j]=down[i][j]=;
                     if(i!=)
                         up[i][j]=up[i-][j]+;
                     if(j!=n-)
                         down[i][j]=down[i][j+]+;
                 }
             }

         ans=max(ans,getMax());
 //-------------------------------
         memset(down,,sizeof down);
         memset(up,,sizeof up);
         for(int i=n-; i>=; i--)
             for(int j=; j<n; j++)
             {
                 if(a[i][j]=='#')
                 {
                     up[i][j]=down[i][j]=;
                 }
                 else
                 {
                     up[i][j]=down[i][j]=;
                     if(i!=n-)
                         up[i][j]=up[i+][j]+;
                     if(j!=)
                         down[i][j]=down[i][j-]+;
                 }
             }

         ans=max(ans,getMax());
 //--------------------------------------------------

         for(int i=; i<n; i++)
             for(int j=; j<n; j++)
             {
                 for(int num=; num<; num++)
                 {
                     dfs(i,j,num);
                 }
             }

         for(int i=; i<n; i++)
             for(int j=; j<n; j++)
             {
                 ans=max(ans,cnt[i][j][]+cnt[i][j][]-);
                 ans=max(ans,cnt[i][j][]+cnt[i][j][]-);
                 ans=max(ans,cnt[i][j][]+cnt[i][j][]-);
                 ans=max(ans,cnt[i][j][]+cnt[i][j][]-);
             }

         cout<<ans<<endl;
     }
     return ;
 }