Today is the 56th consecutive punch card days from NOIP 2019 preliminary round and 40 days.
After school today, but I will never give up brush title. After the last few days brushing Graph Theory II, began to brush often preliminary examination of the question.
Today brush the two questions Euler circuit. In it with a lot of time for this is because not familiar with the concept:
① no circuit exists to FIG Euler, if and only if all the vertices of degree FIG both even and communication with the FIG .
② presence Euler to FIG circuit, if and only if the drawing of all the vertices into an equal degree and this communicates FIG .
However, the communication judgment more difficult, such as:
This figure is not connected graph, but there are Euler path.
This figure does not exist Euler road.
The first question: 1173
This question is commissioning two days.
The first day: no results, but up to 66 points.
The next day: how to deal with the problem side of the record in the answer, get 83 points. FIG connectivity problems later found after 100 points is determined.
AC Code:
The second question: 1174
This question is much simpler compared to 1173. But I forgot to connectivity issues, debugging nearly an hour.
AC Code:
