http://acm.hdu.edu.cn/showproblem.php?pid=4857
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 6665 Accepted Submission(s): 1950
【HDOJ4857】【反向拓扑排序】
原文:https://www.cnblogs.com/MekakuCityActor/p/9145848.html