迷宫城堡
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 10908 Accepted Submission(s): 4887
Problem Description
为了训练小希的方向感,Gardon建立了一座大城堡,里面有N个房间(N<=10000)和M条通道(M<=100000),每个通道都是单向的,就是说若称某通道连通了A房间和B房间,只说明可以通过这个通道由A房间到达B房间,但并不说明通过它可以由B房间到达A房间。Gardon需要请你写个程序确认一下是否任意两个房间都是相互连通的,即:对于任意的i和j,至少存在一条路径可以从房间i到房间j,也存在一条路径可以从房间j到房间i。
Input
输入包含多组数据,输入的第一行有两个数:N和M,接下来的M行每行有两个数a和b,表示了一条通道可以从A房间来到B房间。文件最后以两个0结束。
Output
对于输入的每组数据,如果任意两个房间都是相互连接的,输出"Yes",否则输出"No"。
Sample Input
3 3
1 2
2 3
3 1
3 3
1 2
2 3
3 2
0 0
Sample Output
Yes
No
Author
Gardon
Source
HDU 2006-4 Programming Contest
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