多校预演:http://oj.alpc.cn/en/Contest/Details/?id=17
BC:http://acm.hdu.edu.cn/search.php?field=problem&key=BestCoder+2nd+Anniversary&source=1&searchmode=source
多校1:http://acm.hdu.edu.cn/search.php?field=problem&key=2016+Multi-University+Training+Contest+1&source=1&searchmode=source
题解:http://bestcoder.hdu.edu.cn/blog/2016-multi-university-training-contest-1-solutions-by-hit/
多校2:http://acm.hdu.edu.cn/search.php?field=problem&key=2016+Multi-University+Training+Contest+2&source=1&searchmode=source
题解:https://async.icpc-camp.org/d/493-2016-multi-university-training-contest-2
需要学习的:单调队列、拓扑序排序、RMQ、分桶法