九度教程第92题

题目地址：http://jobdu.sinaapp.com/problem.php?cid=1040&pid=91

测试数据大放送：

4 4 5
S.X.
..X.
..XD
....
3 4 5
S.X.
..X.
...D
2 2 1
S.
.D
8 8 7
.DXS...X
........
XX..XX..
.X.X.X.X
..X.....
X....X..
........
XXXX....
5 4 18
S...
....
....
....
...D
6 6 10
S.....
......
......
......
......
.....D
2 3 2
SDX
..X
2 2 3
SD
..
2 2 2
SD
XX
4 4 6
.S..
XXX.
XXX.
XXXD
5 4 8
S...
.XX.
.X..
.X.X
....
3 3 3333
.S.
...
...
2 2 1
SD
..
1 5 4
S...D
4 5 5
.S...
..X..
.XDX.
..X..
2 4 7
SD..
....
2 2 3
S.
D.
4 4 9
S..X
X.X.
..XD
....
0 0 0

输出：
NO
YES
NO
NO
NO
YES
NO
YES
NO
NO
NO
NO
YES
YES
NO
YES
YES
YES

C语言源码：

#include<stdio.h>
int mark[10][10];
char s[10][10];
int n,m,start1,start2,end1,end2,t,flag;
void dfs(int i,int j,int time)
{
	if(flag==-1)
	{
		if(time==t)
		{
			if(i==end1&&j==end2)
				flag=1;
		}
			else 
			{
				if(i>0&&mark[i-1][j]==-1&&s[i-1][j]!='X')
				{
					if(((time!=t-1)&&s[i-1][j]!='D')||((time==t-1)&&(s[i-1][j]=='D')))
					{
						mark[i-1][j]=1;
						dfs(i-1,j,time+1);
						mark[i-1][j]=-1;
					}
				}
				if(i<n-1&&mark[i+1][j]==-1&&s[i+1][j]!='X')
				{
					if(((time!=t-1)&&s[i+1][j]!='D')||((time==t-1)&&(s[i+1][j]=='D')))
					{
						mark[i+1][j]=1;
						dfs(i+1,j,time+1);
						mark[i+1][j]=-1;
					}
				}
				if(j<m-1&&mark[i][j+1]==-1&&s[i][j+1]!='X')
				{
					if(((time!=t-1)&&s[i][j+1]!='D')||((time==t-1)&&(s[i][j+1]=='D')))
					{
						mark[i][j+1]=1;
						dfs(i,j+1,time+1);
						mark[i][j+1]=-1;
					}
				}
				if(j>0&&mark[i][j-1]==-1&&s[i][j-1]!='X')
				{
					if(((time!=t-1)&&s[i][j-1]!='D')||((time==t-1)&&(s[i][j-1]=='D')))
					{
						mark[i][j-1]=1;
						dfs(i,j-1,time+1);
						mark[i][j-1]=-1;
					}
				}
		}
	}
}		
int main()
{
	int i,j;
	scanf("%d %d %d",&n,&m,&t);
	while(n||m||t)
	{
		for(i=0;i<n;i++)
			scanf("%s",s[i]);
		for(i=0;i<n;i++)
			for(j=0;j<m;j++)
				mark[i][j]=-1;
		for(i=0;i<n;i++)
			for(j=0;j<m;j++)
				if(s[i][j]=='S')
					goto loop1;
		loop1:start1=i;
		start2=j;
		for(i=0;i<n;i++)
			for(j=0;j<m;j++)
				if(s[i][j]=='D')
					goto loop2;
		loop2:end1=i;
		end2=j;
		flag=-1;
		mark[start1][start2]=1;
		dfs(start1,start2,0);
		if(flag==-1)
			printf("NO\n");
		else
			printf("YES\n");
		scanf("%d %d %d",&n,&m,&t);
	}
}