poj 2530 Tetris Alphabet 模拟

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

char str[55][25],tmp[55][25],ans[27];
int n,flag;

int judge(int x,int y,char ch)
{
int j;
for (j=x;j<n;j++)
{
if (str[j][y]>='A'&&str[j][y]<='Z'&&str[j][y]!=ch)
{
flag=1;return 1;
}
}
return 0;
}

void dfs(int x,int y,char ch)
{
int i,j,row,col,dir[4][2]={-1,0,1,0,0,-1,0,1};
for (i=0;i<4;i++)
{
row=dir[i][0]+x;
col=dir[i][1]+y;
if (row<n&&col<20&&row>=0&&col>=0&&tmp[row][col]==ch)
{
if(judge(row,col,ch))return;
tmp[row][col]='.';
dfs(row,col,ch);
if(flag)tmp[row][col]=ch;
}
}
}

void slove1()
{
int i,j,k=0;
for (j=0;j<20;j++)
{
for (i=n-1;i>=0;i--)
{
flag=0;
if (tmp[i][j]!='.')
{
tmp[i][j]='.';
if(!judge(i,j,str[i][j]))
dfs(i,j,str[i][j]);
if(flag)tmp[i][j]=str[i][j];
else ans[k++]=str[i][j];
break;
}
}
}
sort(ans,ans+k);
printf("%c",ans[0]);
}

void slove2()
{
int i,j;
for (j=0;j<20;j++)
{
for (i=n-1;i>=0;i--)
{
if (tmp[i][j]==ans[0])
{
tmp[i][j]='.';
dfs(i,j,ans[0]);
return;
}
}
}
}

void Copy1()
{
int i;
for (i=0;i<n;i++)strcpy(tmp[i],str[i]);
}

void Copy2()
{
int i;
for (i=0;i<n;i++)strcpy(str[i],tmp[i]);
}

int main()
{
int i,j,num=0,vis[27]={0};
scanf("%d",&n);
for (i=0;i<n;i++)
{
scanf("%s",str[i]);
strcpy(tmp[i],str[i]);
for(j=0;j<20;j++)
{
if(str[i][j]!='.'&&!vis[str[i][j]-'A'])
{
vis[str[i][j]-'A']=1;
num++;
}
}
}
for (i=0;i<num;i++)
{
slove1();
Copy1();
slove2();
Copy2();
}
printf("\n");
return 0;
}