Four Colors (jp.netfarm.yonshoku) on Google Play
"Any map can be colored using four colors?!"This conjecture, proposed in the 19th century, was solved in the late 20th century after more than 100 years.Now it's time for you to experience the so-called Four-Color Theorem.The rule is: Color the regions in such a way that regions sharing a common boundary do not share the same color.You have only four colors, red, blue, green, and yellow.Easy to difficult 40 stages.