Solving the region-coloring problem

Let's use the constraint satisfaction framework to solve the region-coloring problem. Consider the following screenshot:

Figure 7: Framework for the region-coloring problem

We have a few regions in the preceding figure that are labeled with names. The goal is to color with four colors so that no adjacent regions have the same color.

Create a new Python file and import the following packages:

from simpleai.search import CspProblem, backtrack

Define the constraint that specifies that the values should be different:

# Define the function that imposes the constraint 
# that neighbors should be different
def constraint_func(names, values):
    return values[0] != values[1]

Define the main function and specify the list of names:

if __name__=='__main__':
    # Specify the variables
    names = ('Mark', 'Julia', 'Steve', 'Amanda', 'Brian',
        ...