GATE | GATE CS 2018 | Question 12
The chromatic number of the following graph is _________ .
Note – This was Numerical Type question.
Explanation: Chromatic number of given graph is 3.
Note that graph is Planar so Chromatic number should be less than or equal to 4 and can not be less than 3 because of odd length cycle. In other words if a graph is planar and has odd length cycle then Chromatic number can be either 3 or 4 only.