I don't think you proved the sufficiency in the Euler problem. Counter-example: Imagine two disconnected triangles. 6 points each with 2 degrees. I presume the graph needs to be connected for sufficiency. But video offered no proof even in this case. For the original problem, let U, D, L, R be the number of moves in the Up, Down, Left and Right directions respectively. Then D - U = 2, L = R and U + D + L + R = 17 necessarily, which is impossible. [Q.E.D.] But I indeed enjoy your series very much and I have learned quite a lot. Many thanks.
@alenpete84805 жыл бұрын
Plz notice the constrain: a CONNECTED unidirectional graph.
@vlpubmed47365 жыл бұрын
@@alenpete8480 Thanks Pete. That's what I thought.