2020牛客多校三 E Two Matchings

https://ac.nowcoder.com/acm/contest/5668/E 这篇blog写的不错https://www.cnblogs.com/whitelily/p/13338146.htmlhtml #include<bits/stdc++.h> using namespace std; const int maxn=200000+100; int T,n; long long a

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