【USACO2-1-1】城堡 The Castle dfs

原题

//一道第二章的题拖到了现在 写了半小时调了半小时好菜啊qwq

用leftt[][],rightt[][],up[][],down[][]来记录四周有木有墙

一开始先dfs确定有多少房间并标号

然后从最西最南开始枚举,拆了墙的话最大是多少,最后输出即可。

#include
#include
#include
#include
#include
#define N 101
using namespace std;
mapmp2;
char ans_c;
int up[N][N],down[N][N],leftt[N][N],rightt[N][N],mp[N][N],rec[N][N];
int large[N*N],dy[4]={-1,0,0,1},dx[4]={0,1,-1,0};
int n,m,id,ans_x,ans_y,ans_size,ans_size2,ans_dir;
bool judge(int x,int y){return x>=1&&x<=n&&y>=1&&y<=m;}
int read()
{
	int f=1,ret=0;char ch=getchar();
	for (;!isdigit(ch);ch=getchar()) if (ch=='-') f=-1;
	for (;isdigit(ch);ch=getchar()) ret=ret*10+ch-'0';
	return f*ret;
}
void handle(int x,int y)
{
	for (int i=1;i<=mp[x][y];i<<=1)
	{
		if (mp[x][y]&i) 
		{
			if (i==1) leftt[x][y]=1;
			if (i==2) up[x][y]=1;
			if (i==4) rightt[x][y]=1;
			if (i==8) down[x][y]=1;
		}
	}
}
void dfs(int x,int y,int id)
{
	if (rec[x][y]) return;
	large[id]++;rec[x][y]=id;
	if (!leftt[x][y]&&judge(x,y-1)) dfs(x,y-1,id);
	if (!rightt[x][y]&&judge(x,y+1)) dfs(x,y+1,id);
	if (!up[x][y]&&judge(x-1,y)) dfs(x-1,y,id);
	if (!down[x][y]&&judge(x+1,y)) dfs(x+1,y,id);
}
int main()
{	
	m=read();n=read();
	for (int i=1;i<=n;i++)
		for (int j=1;j<=m;j++)
		{
			mp[i][j]=read();
			handle(i,j);
		}
	for (int i=1;i<=n;i++)
		for (int j=1;j<=m;j++)
		{
			if (!rec[i][j])
			{
				dfs(i,j,++id);
				if (large[id]>ans_size) ans_size=large[id];
			}
		}
	/*for (int i=1;i<=n;i++)
	{
		for (int j=1;j<=m;j++) printf("%d ",rec[i][j]);
		printf("\n");
	}*/
	for (int j=1;j<=m;j++)
		for (int i=n;i>=1;i--)
		{
			for (int k=0;k<4;k++)
			{
				int x=i+dx[k],y=j+dy[k];
				if (judge(x,y)&&rec[x][y]!=rec[i][j]&&ans_size2

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