We have a JavaScript applet: https://www.kleemans.ch/four-color-theorem-map-solver We draw a contour only by thick black straight lines. When you press "Solve" button, areas are colored, according to the 4 colors theorem, no more than 4 colors. Under the table for painting, there are several prepared examples. The program can be downloaded here: https://github.com/akleemans/fourcolors It seems that everything is working properly. The problem arises when we put another contours into the folder "examples". Here is the version with contours, which I created in Paint: https://drive.google.com/file/d/0B-u7dqmskzd5c0lDdDRGc1dMY1E/view The program colors my contours areas (the first five examples), more than four colors. I don't know why it happens. I wrote in this matter to the author, but he isn't responding. I completely don't know JavaScript. I only know that this code line stops procedure after 10 seconds: if (millis () - start> 10 * 1000) {break; } Code (markup): If we delete this line, the browser crashes error. I will be grateful for any help. Maybe someone of you knows any simpler way to realize idea of coloring the contours areas using 4 colors theorem? Maybe there are any other programs? It seems to me that this applet has everything what I need and it's necessary to modify it only just a little.