【CCF 201312-5】I’m stuck! DFSApare_xzc

[CCF 201312-5] I’m stuck!

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题面

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Sample input

5 5
--+-+
..|#.
..|##
S-+-T
####.

Sample output

2

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思路:

1. 从起点S开始做dfs, 记录所有起点可达的点(S,T除外)

2.对于每个起点可达的点，做dfs，如果无法到达T, 则答案数ans加一

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代码：

/*
I'm stuck CCF 201312-5
2019/11/21 xzc 100
*/
#include <bits/stdc++.h>
using namespace std;
char a[60][60];
int Tx,Ty,Sx,Sy,r,c;
//          下 上 右 左 
int dx[] = { 1,-1, 0, 0 };
int dy[] = { 0, 0, 1,-1 };
bool vis[60][60];
bool ok(int x,int y)
{
	return (x>=0&&x<r&&y>=0&&y<c&&a[x][y]!='#'&&!vis[x][y]);
}
vector<pair<int,int> > V; 
void dfs(int x,int y)
{
	if(a[x][y]!='S'&&a[x][y]!='T') V.push_back(make_pair(x,y));
	vis[x][y] = true;
	int down = 0, up = 4;
	if(a[x][y]=='-') down = 2, up = 4;
	else if(a[x][y]=='|') down = 0, up = 2;
	else if(a[x][y]=='.') down = 0, up = 1;
	for(int i=down;i<up;++i)
	{
		int xx = x+dx[i], yy = y+dy[i];
		if(!ok(xx,yy)) continue;
		dfs(xx,yy);
	}		
}
void judge(int x,int y)
{
	vis[x][y] = true;
	if(vis[Tx][Ty]) return;
	int down = 0, up = 4;
	if(a[x][y]=='-') down = 2, up = 4;
	else if(a[x][y]=='|') down = 0, up = 2;
	else if(a[x][y]=='.') down = 0, up = 1;
	for(int i=down;i<up;++i)
	{
		int xx = x+dx[i], yy = y+dy[i];
		if(!ok(xx,yy)) continue;
		dfs(xx,yy);
	}		
}
int main()
{
	scanf("%d%d",&r,&c);
	for(int i=0;i<r;++i)
	{
		scanf("%s",a[i]);
		for(int j=0;j<c;++j)
		{
			if(a[i][j]=='S') Sx=i,Sy=j;
			else if(a[i][j]=='T') Tx=i,Ty=j; 	
		} 
	}
	dfs(Sx,Sy);
	if(!vis[Tx][Ty])
	{
		printf("I'm stuck!
");return 0;
	}
	int sz = V.size(),ans=0;
	for(int i=0;i<sz;++i)
	{
		memset(vis,false,sizeof(vis));
		judge(V[i].first,V[i].second);
		if(!vis[Tx][Ty]) ++ans;
	}
	printf("%d
",ans);
	
	return 0;
}

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AK啦~