考虑对于一棵树$G$,这个问题的答案-- 当$k$为奇数时答案显然为0,否则从$V$中任选$k$个点,以任意一点为根,从底往上不难发现子图数量唯一 换言之,当$k$为偶数时,每一个合法(恰有$k$个奇度数的点)子图恰好对应于一种选择方案,即${|V|\choose k}$ 当$G$是一张连通图时,继续来分析答案-- 首先$k$仍要是偶数,且仍然考虑任选$k$点,并求出其一棵生成树 对于生成树以外的边,任意选每一条边是否加入子图,之后同样可以通过这棵生成树构造出一组方案,换言之每一组选点方案恰对应…

D. Regular Bridge time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output An undirected graph is called k-regular, if the degrees of all its vertices are equal k. An edge of a connected graph is c…

1126. Eulerian Path (25) 时间限制 300 ms 内存限制 65536 kB 代码长度限制 16000 B 判题程序 Standard 作者 CHEN, Yue In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which starts…

In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which starts and ends on the same vertex. They were first discussed by Leonhard Euler while solving the fa…

In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which starts and ends on the same vertex. They were first discussed by Leonhard Euler while solving the fa…

1126 Eulerian Path (25 分) In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which starts and ends on the same vertex. They were first discussed by Leonhard…

1126. Eulerian Path (25) 时间限制 300 ms 内存限制 65536 kB 代码长度限制 16000 B 判题程序 Standard 作者 CHEN, Yue In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which starts…

https://pintia.cn/problem-sets/994805342720868352/problems/994805349851185152 In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which starts and ends on the…

  计蒜客)翻硬币 //暴力匹配 #include<cstdio> #include<cstring> #define CLR(a, b) memset((a), (b), sizeof((a))) using namespace std; int n, m, t; int main() { int i, j, x; scanf("%d", &t); while(t--) { scanf("%d%d", &n, &m)…

1126 Eulerian Path (25 分) In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which starts and ends on the same vertex. They were first discussed by Leonhard…