Handshaking lemma
In graph theory, a branch of mathematics, the handshaking lemma is the statement that every finite undirected graph has an even number of vertices with odd degree (the number of edges touching the vertex).
Railroad is one of the challenges that can be solved using this lemma.
Solution is if 4X +3Y ≡ 0 mod 2, then possible. Otherwise, it is impossible.
And it can be reduced to just checking whether Y is even or odd.
Comments
Post a Comment